glossary of model making terms

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acrylic – Poly(methyl methacrylate) (PMMA) or poly(methyl 2-methylpropenoate) is the synthetic polymer of methyl methacrylate. This thermoplastic and transparent plastic is known under the tradenames Plexiglas, Limacryl, R-Cast, Perspex, Plazcryl, Acrylex, Acrylite, Acrylplast, Altuglas, Polycast, Oroglass and Lucite and is commonly called acrylic glass or simply acrylic.

Acrylic is used as an alternative to glass. Therefore it is the material of preferred choice for fabrication of protective covers and display cases for scale models and replicas. Acrylic is in competition with polycarbonate. It is often preferred on account of its moderate properties, easy handling and processing and low cost, however acrylic is much less stress and impact resistant than polycarbonate.


AFV – Abbreviation for Armored Fighting Vehicles, which are popular and frequent object for scale replication.

appearance model – Type of prototype. Represents the external look of the future product. Usually non-functional, unlike the engineering models.


articulation – Any removable, interchangeable, or moving parts. A part of model’s functionality





cast – In sculpting and model making: 1. Outer hard shell over large mold, which supports soft, thin inner layer of RTV rubber. 2. Reinforcement layer made of fiberglass or reinforced plaster over the object made of weaker substance. For example, over styrofoam topography for architectural model.


casting (process) – Replication process, pouring into a mold liquid casting material, resin or metal, which cures later as a result of chemical reaction or cooling.


casting (object) – Cured hard copy, replica, produced by casting liquid material in RTV or other made mold.


CNC – stands for Computer Numerical Control. CNC controller reads, interprets a data uploaded in it and drives the tool, which create desirable configuration out of the block of raw material by selective removal of it. CNC carving is one of the rapid prototyping techniques. It is widely used in model making for creating topographical models, prototypes and various parts.


collectible – In relation to model making – any scale model, replica, miniature or figurine, developed specifically for collectors of such items.


color casting – Resin casting using material mixed with a color pigment in order to receive castings which are colored instantly. Being used for prototyping and in mass production.

Color casting - samples


composites – Common term for the large family of engineered materials made of small fibers and particles, mixed with binding substance and formed into blocks and boards under high pressure and temperature. There are wooden based, plastic based and mixed composites. All composites are being widely used in modern model making due to their durability and, in some cases, lightweight. Composites are vary by density. The most popular composites in model making industry are MDF, RenShape and tooling boards.



desktop model – Scale replica, usually not larger than 15”, mounted on a display/base/pedestal for keeping on a desk or shelf.


detailing – Representation of major, main and precise details on scale model or replica. Level of detailing is important part of model’s requirements. Click here for detailed descriptions of Levels of Detailing.


diorama – A scaled down scene of various content. There are two main types of dioramas: Constant Scale Diorama and Perspective Scale Diorama.

Constant Scale Diorama also being called Walk Around Diorama and it represents all its elements in the same, constant scale. It can be small and consist of just a few elements (many collectibles are designed as small dioramas) or it can be large and consist of dozens or even hundreds elements. Large dioramas of this type are being commissioned for museums and exhibits. Needless to say, that all architectural and urban models are, in fact, Constant Scale Dioramas.

Perspective Scale Dioramas are being used mostly in museums, installed into the wall, which places the observer in front of it, facing the front plan of the diorama, which is represented in larger scale. A scale of the diorama becomes smaller and smaller to the depth of it, until the physical diorama ends with painted background, which creates a visual illusion of much greater depth and area covered.


duo chrome – Two color painting scheme.



effects – Additional features, such as lights, sound, movements and visual effects, which might be added to the model, replica or diorama. Effects are a part of model’s functionality.


engineered models – Type of prototype. In addition to the external look of the future product represents also the interior engineering including enclosed mechanisms and electronics, if apply. The purpose of engineered model is to present the future product as close as possible to its look and function when it will be produced.


epoxy – A material from the family of resins, which still be in use in model making, although urethane resins are much more preferable today, as urethanes is almost odorless and have better characteristics. Epoxy (or Polyepoxide) is a polymer that cures when mixed with a catalyzing agent (hardener) based on a reaction between epichlorohydrin and bisphenol-A. Epoxy is one of the veterans in resins family. First attempts to synthesize commercial resins from epichlorohydrin started in US in 1927. However the attempts succeeded only in 1936.

Epoxy being used today in model making industry mostly as glue. Theoretically it can be cast in RTV molds; however it cannot be compared to urethane resins which are the preferred if not only choice for resin casting.

For the long time epoxy was the preferred choice for fiberglass, which also is changing due to development of odorless and cost effective urethane resins.


exhibit model – Any type of scale model, replica or constant scale diorama which is commissioned for exhibition. By their characteristics such models are closely similar to museum models. However, unlike most of museum models, exhibit models are meant to be moved frequently, therefore, should be more durable than museum models. Exhibit models usually required to be accompanied by transit case.



FDM – Stands for Fused Deposition Modeling. Rapid prototyping technique.


fiberglass – custom reinforced shell formed by laying down multiple layers of fiberglass fabric dipped in polymer resin, such as epoxy or polyurethane..


figurine – Scaled down representation of human, animal or other character. Figurine or group of figurines might be itself a collectible miniature, partially or entirely; or might be used as scenery elements.


foams – Large family of engineered materials, formed by trapping large quantity of air bubbles in liquid polymer that becomes hard as a result of chemical reaction or cooling. Foams are vary by chemical origin and density and used widely in the model making industry. The handiest ones are Styrofoam and high density foams, which come as blocks and boards. High density foams are a default material for CNC carving, prototype making and creating patterns for vacuum-forming.


functionality – Important characteristic of the scale model. It includes articulation, effects and interactivity.







interactivity – Is a complex of features, which allows interaction with the model in order to provide optional or additional information about the subject/s. Interactivity is a part of model’s functionality. In order to run and control such features the model is accompanied by specially designed Interactive System (IS).


interactive system (IS) – Specially designed system for controlling the interactive features, such as effects, LED and fiber optic marks, narratory and video clip demonstration. IS can be controlled via simple control board or via computer using standard and custom designed software. 







laser cutting – It is popular in model making, especially in architectural model making, technology based on cutting parts out of sheet of material using high power laser. The output of the laser is being directed by computer software. Due to this technology the process of cutting walls along with doors and windows for architectural models as well as other flat parts become faster and much more efficient.


laser engraving – Same process as laser cutting, being performed using the same equipment. The difference is that the laser beam does not go through the material, but half-way, engraving ornament or pattern according to the software input. The technology is most useful in architectural model making and sign making/engraving.


level of detailing – Recognized levels of detailing are Low, Medium, High and Museum as well as sublevels, or transitional levels, such as Medium to High or High to Museum. Click here for detailed descriptions of Levels of Detailing.



macro scale – A contrary to the regular scale. Usually scale model is smaller than its origin. Scale model in macro scale is larger than its origin. For example, macro scale model of an insect or molecule.


maquette – A rare French word for scale model. Usually used to define a very general, low detailed model, built for quick study or to compose elements of future high detailed scale model, sculpture or collectible. It is incorrect to use word maquette to define a highly detailed scale model or replica


master – Also being called sometimes master-model. It is original scale model or sculpture created for further replication. Masters should be designed in accordance with specific requirements to a particular replication process and a type of mold, which will be used.


MDF – Stands for Medium Density Fiberboard. It is one of the most useful wooden composites, durable and cost effective.


micro scene – Same as miniature.


micro set – Scaled down set for movie and TV production.


miniature – Small collectible diorama, figurine or group of figurines. Miniature might be scaled down precisely or be whimsical.


model – See scale model.


model-type – Describes type of the model. Click here to be redirected to the Classification of Scale Models.


model-purpose – Describes purpose of the model. Click here to be redirected to the Classification of Scale Models.


mold (mould) – In industrial replication – a negative of the master, a form, in which castings are being made by pouring into the mold liquid material, which after curing become a hard copies (replicas) of the master. Molds are differing by material of which they are made and their construction, depending on type of technology for which a mold is created. The most useful molds in model making industry are silicone rubber or RTV molds, used for resin casting.


monochrome – One color painting scheme.


multi-color – Painting scheme of more than three colors.


museum model – Any scale model, scale replica or diorama meant to be a part of museum exhibit. Usually museum model are of the highest level of detailing. Also, museum models should be fabricated in accordance to the requirements for conservation and preservation of the museum model, in order to insure a long life of the model. The most important and difficult task here is a use of primarily acid free materials and to seal and conserve materials that still might contain acid which affects the model’s coloration, properties of materials and glue’s strength. Properly built and preserved museum model or diorama should be able to be exhibited for 40 – 50 years without repair and restoration.





optional features – We use the term optional features for the items which are accompanying the model and serve to protect and/or display the model. Optional features include clear protective covers, displays/pedestals and transit cases.

Clear protective cover is made of clear plastic or glass, with or without frame. It is being installed on the model’s base, preventing it from dust, humidity and touching. Protective cover is a must for architectural model.

Displays/Pedestals are designed for the model, according to its size, level of detailing and color scale and custom finished by painting, plain or textured, stained wood or other desired finish.

Transit Case is a necessity when it comes to exhibit models and other models which are meant for frequent transportation. Transit cases are differing by material and design depending on model’s size, design and purpose.



PETG – Plastic, glycol-modified polyethylene terephthalate, it is a copolyester that is a clear amorphous thermoplastic. PETG sheet has high stiffness, hardness, and toughness as well as good impact strength. Used to fabricate clear parts and as raw material for vacuum-forming.


pewter – Is a metal alloy, traditionally between 85 and 99 percent tin, with the remainder consisting of copper and antimony, acting as hardeners, with the addition of lead for the lower grades of pewter, which have a bluish tint. Process of pewter casting is relatively easy and equipment is affordable for a small shop, which made it very popular and recognizable for producing limited edition collectibles, figurines as well as scenery elements and small parts for model making.


polycarbonate – Plastic, one of the thermoplastic polymers. Polycarbonate is a very lean clear material, temperature and impact resistant, good for fabrication and thermoforming. Because of its clarity it is the best choice for windows on architectural and other models.


polyethylene – Plastic, one of the thermoplastic polymers. Heavily used in consumer products, especially toys. Over 60 million tons of the material is produced worldwide every year. Rarely used in actual model making.


polyester – (aka Terylene) is a category of polymers which contain the ester functional group in their main chain. Although polyesters come in many different forms, in model making and collectible production the most useful is a polyester resin (or polyester amber). Highly toxic, with strong unpleasant odor in its uncured form, polyester resin was widely used as a casting material before it was replaced by safe and odorless urethanes. Polyester resin mixed with stone/marble powder resembles marble, ceramic or bisque porcelain, therefore it called sometimes “Artificial marble”. In this form it is heavily used by collectibles/dιcor manufacturers in China for production of figurines, home dιcor ornaments and other items. Coming from Chinese manufacturers it is known as “Polyresin” or “Resinic”.


polystyrene (Polyphenylethene) – Is an aromatic polymer made from the aromatic monomer styrene. Polystyrene is a thermoplastic substance, normally existing in solid state at room temperature, but melting if heated (for molding or extrusion), and becoming solid again when cooling off, therefore, it used both, for fabrication and thermo/vacuum-forming.

Pure solid polystyrene is a colorless, hard plastic with limited flexibility. Polystyrene is usually white, although it can be transparent or can be made to take on various colors. It is economical and is used for producing plastic model assembly kits, license plate frames, plastic cutlery, CD "jewel" cases, and many other objects where a fairly rigid, economical plastic is desired.


polystyrene foam – See Styrofoam.


polyurethane – A family of polymers consisting of a chain of organic units joined by urethane links.

Polyurethane products are often called "urethanes". They should not be confused with the specific substance urethane, also known as ethyl carbamate. Polyurethanes are not produced from ethyl carbamate, nor do they contain it.

Polyurethane polymers are formed by reacting a monomer containing at least two isocyanate functional groups with another monomer containing at least two alcohol groups in the presence of a catalyst.

Polyurethane formulations cover an extremely wide range of stiffness, hardness, and densities and therefore are widely used in flexible foam seating, rigid foam insulation panels, microcellular foam seals and gaskets, elastomer wheels and tires, electrical potting compounds, high performance adhesives and sealants, carpet underlay, and for many other purposes.

Polyurethanes in different forms are heavily used in modern model making, mostly as tooling blocks and boards and as resin casting materials of first choice. Polyurethane resins are rightfully replacing older traditional materials that were used in model making.


photo-etching – It is a photochemical process which was initially developed to produce printed circuit boards, adopted by model makers and become one of the preferred and highly efficient methods of microfabrication. Photo-etching (aka photolithography) shares some fundamental principles with photography. A thin sheet of metal, brass or silver, covered with etching agent is being exposed to the light which activates the etching agent. The desired part/pattern protected by optical mask resists, other areas are being etched through or half-through, resulting in highly precise flat parts.


PVC – Stands for Polyvinyl Chloride. It is a widely used thermoplastic polymer. In terms of revenue generated, it is one of the most valuable products of the chemical industry. Around the world, over 50% of PVC manufactured is used in construction. As a building material, PVC is cheap, durable, and easy to assemble. In recent years, PVC has been replacing traditional building materials such as wood, concrete and even metal in many areas. Same properties as well as availability of wide variety of pre-manufactured tubes and profiles made PVC one of the preferred plastics used in model making.


PVC foam – One of PVC applications received from chemically foamed PVC. It comes in sheets of various thicknesses. The main properties of PVC foam sheets are light weight, high impact strength, fine closed cell structure and low flammability. They are easy to cut, saw, drill, and glue. PVC foam sheets in many situations are preferable even toward the very traditional and popular materials in model making, such as styrene and MDF.


plastics – Is the general term for a very wide range of synthetic or semi-synthetic products of polymerization. They are composed of organic condensation or addition polymers and may contain other substances to improve performance or reduce costs. Plastics vary by their properties and therefore used for different purposes. Plastics, such as styrene, polycarbonate, PVC, PVC foam, PETG are the preferred, recognizable and widely used in model making.


product development – A process of new consumer product’s development, including both technical development and marketing. Model making industry provides a wide range of product development related services including concept development, prototype and master making, and testing. Product development is a long and complex process, it requires professional expertise and proper funding.


prop – A theatrical/movie/TV property, any object held, used or touched on stage/set by an actor in accordance to script requirements or as deemed by the director. Design, fabrication and replication of such objects for theater/movie/TV production is a common service provided by most of general model makers.


prototype – A representation of future product, its model in 1:1 scale. The term “prototype” derives from the Greek words "πρώτος" [protos] which means "the first one", and "τύπος" [teepos], which means "kind, type, sort, form". Prototypes are being fabricated practically of every consumer product in order to study, develop and present the future product. There are certain types of prototypes depending on their purpose and target for representation. “Appearance model” and “Engineered model” (aka Production Prototype) are the most common types.


protective cover – See optional features.





rapid prototyping – A process of automatic manufacturing a physical object via interpretation of virtual model and transferring this data into the physical space. Common feature of such techniques is an input of CAD (Computer Aided Design) or animation modeling software based 3D virtual model of the desired object. Computer than transforms it into thin, virtual, horizontal cross-sections and then creates each cross-section in physical space, one after the next until the model is finished. It is a WYSIWYG (What-You-See-Is-What-You-Get) process where the virtual model and the physical model correspond almost identically. Rapid prototyping techniques became one of the most used for creating simpler prototypes, models and model parts. The most recognizable and used rapid prototyping techniques are SLS, SLA, CNC machining and FDM.


RC – Stands for Radio Controlled. Radio controlled models is a very popular field of hobby model making. Professional model makers are involved in development of such models for the industry producing models and model kits for RC modeling enthusiasts.


RenShape – A high density composite material. It comes in form of 2” -4” boards, highly durable, easily machinable. Used for making models, parts, prototypes and patterns for vacuum-forming.


requirements (model requirements) – A description of the scale model, summarizing its features. It includes type of the model, its purpose, scale and size, main elements, level of detailing, functionality and optional features. Accurate requirements allow the model maker to evaluate the project, its complexity, time needed for its production and to quote the project accordingly.


reinforcement – Interior or exterior structure/shell supporting and reinforcing weaker parts and areas.


replica – See scale replica.


resin – A common term, defining a family of liquid multi component plastics which being used for resin casting in RTV molds, creating fiberglass and some other purposes. Resins include mostly urethanes, epoxy and polyester.  


RTV (RTV silicone or silicone rubber) – RTV stands for Room Temperature Vulcanizing. RTV silicone rubber in model making and resin casting is a primary choice, usually two-component material for creating molds.



scale – The main characteristic of any scale model/replica, defining relation of model’s size to the size of original. Click here to find more information about scales and scale selection.


scale model – a physical representation of a subject/scene that is smaller or, in some cases, larger than an origin.


scale replica – Same as scale model. The difference between the two terms is that scale model is a representation of a preexisted or imaginary subject or scene. Scale replica represents only a preexisted subject.


scenery (scenery elements) – In model making, mostly in architectural model making - various elements, such as people figurines, cars and other vehicles, equipment and others, added to the model so the observer could visually compare the model/project to the objects of familiar size and, therefore, have an accurate impression of the project’s size. Scenery elements also add to the model some action and sense of realism. Adding high quality realistically looking scenery elements to the presentation, sales and museum models is very important.


silicone rubber – See RTV.


SLA – Stands for Stereolithography. Rapid prototyping technique.


SLS – Stands for Selective Laser Sintering. Rapid prototyping technique.


styrene – A second, frequently used name for polystyrene, the most used plastic material in model making. In fact, styrene is not polystyrene itself. Also known as vinyl benzene, it is an organic compound which, under normal conditions, is an oily liquid. Styrene is the precursor to polystyrene.


styrofoam – A trademark for polystyrene thermal insulation, a material manufactured by Dow Chemical Company. The word styrofoam often used by the general public in the United States and Canada as a generic term for any type of polystyrene foam, although it is not entirely correct.

In 1941, researchers in Dow's Chemical Physics Lab found a way to produce polystyrene as closed cell foam that resisted moisture. Because the material proved to be unsinkable, it was fast adopted by the U.S. Coast Guard for use in a six-person life raft.

Trademarked Styrofoam and polystyrene foam are widely used in construction as insulation. In model making Styrofoam is the preferred choice material for building topographical models, topographies for architectural models and in other cases when model maker has to build larger mass out of cheap, lightweight and sturdy material.


STL – stands for Standard Template Library. This is a file format native to the Stereolithography (SLA). Practically every modern 3D design software has an option to save a 3D model in .stl format in order to produce it by SLA or similar technology.



tooling board – A polyurethane, composite or high-density foam tooling and modeling product created specifically for use in model making, as a raw material for creating solid models, prototypes, mold and foundry patterns and for all other purposes where a uniform, grain-free, dimensionally stable substrate is desired.


topographical model – A scale model covering very large area and representing only its topographical features, built usually in very small scale, less than 1:5,000.


transit case – See optional features.


tri chrome – Three color painting scheme.



urban model – An architectural model typically built at a much smaller scale (starting from 1:500 and less, 1:700, 1:1000, 1:1200, 1:2000, 1:2000, representing several city blocks, even whole town or village, large resort, campus, industrial facility, military base and such. Urban models are a vital tool for town/city planning and development.


urethane – The word urethane often used by the general public and model makers as a shorter name for polyurethane. In fact, urethane (Ethyl Carbamate) is not a component of polyurethanes. Urethane is an ester of carbamic acid. This substance was first prepared in the nineteenth century, was used in pharmaceutical industry, did not prove itself, and after a while has been withdrawn from pharmaceutical use by US FDA.



vacuum-forming – Also known as vacuforming or vacuform, is a simplified version of thermoforming, whereby a plastic sheet is heated to a forming temperature, stretched onto a single-surface pattern or into a single-surface hard mold, and held against the pattern or mold by applying vacuum between the mold surface and the plastic sheet.

The vacuum forming process can be used in model making to make complex configured hollow parts for models and prototypes and product packaging.

Normally, draft angles must be present in the design on the mold for easy release of the formed plastic.

Vacuum forming is usually restricted to forming plastic parts that are rather shallow in depth, otherwise a plastic sheet is formed into thin wall, structurally weak cavity.

Suitable materials for use in vacuum forming are conventionally thermoplastics, the most common and easiest being polystyrene.

Vacuum forming is also appropriate for transparent materials such as PETG and acrylic which are widely used to produce clear domes and skylights for architectural models, canopies and windows for aerospace replicas and such.



whimsical – A term used in collectible design and sculpting, defining fanciful artistic style, a contrary to precise scaling and representation.


white metal – See pewter.










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