glossary of model making terms
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
Armored Fighting Vehicles, which are popular
and frequent object for scale replication.
appearance model –
prototype. Represents the external look of
the future product. Usually non-functional,
unlike the engineering models.
interchangeable, or moving parts. A part of
– 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.
– Replication process, pouring into a mold
liquid casting material, resin or metal,
which cures later as a result of chemical
reaction or cooling.
– Cured hard copy, replica, produced by casting
liquid material in RTV or other made mold.
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.
– In relation to model making – any scale
model, replica, miniature or
figurine, developed specifically for
collectors of such items.
– 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
– 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
usually not larger than 15”, mounted on a
display/base/pedestal for keeping on a desk or
– Representation of major, main and precise
details on scale model or replica.
Level of detailing is important part of
Click here for detailed
descriptions of Levels of Detailing.
– A scaled down scene of various content. There
are two main types of dioramas: Constant
Scale Diorama and Perspective Scale
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
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.
– Two color painting scheme.
– 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
– 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.
– 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
– 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
– Stands for Fused Deposition Modeling.
Rapid prototyping technique.
– custom reinforced shell formed by laying down multiple layers of fiberglass fabric dipped in polymer resin, such as epoxy or polyurethane..
– 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.
– 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
– Important characteristic of the scale model.
It includes articulation, effects
– 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.
– 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.
– 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
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.
– 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
– 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.
– 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.
– Stands for Medium Density Fiberboard.
It is one of the most useful wooden composites,
durable and cost effective.
– Same as miniature.
– Scaled down set for movie and TV production.
– Small collectible diorama, figurine or group
of figurines. Miniature might be scaled down
precisely or be whimsical.
– See scale model.
– Describes type of the model. Click here to
be redirected to the Classification of Scale
– Describes purpose of the model. Click here
to be redirected to the Classification of Scale
– 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.
– One color painting scheme.
– Painting scheme of more than three colors.
– 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
– 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
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.
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.
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.
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
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
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
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/décor
manufacturers in China for production of
figurines, home décor ornaments and other items.
Coming from Chinese manufacturers it is known as
“Polyresin” or “Resinic”.
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.
– 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.
– 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
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.
– 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
– 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
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
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.
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.
– 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.
– See optional features.
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
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.
– 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
– 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
– 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
– Interior or exterior structure/shell
supporting and reinforcing weaker parts and
– See scale replica.
– 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
– 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.
– 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.
a physical representation of a subject/scene
that is smaller or, in some cases, larger than
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.
– 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
– See RTV.
– Stands for Stereolithography. Rapid
– Stands for Selective Laser Sintering.
Rapid prototyping technique.
– A second, frequently used name for
polystyrene, the most used plastic material
in model making. In fact, styrene is not
Also known as vinyl benzene, it is an
organic compound which, under normal conditions,
is an oily liquid. Styrene is the precursor to
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
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
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
– 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.
– A scale model covering very large area and
representing only its topographical features,
built usually in very small scale, less than
– See optional features.
– Three color painting scheme.
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.
The word urethane often used by the
general public and model makers as a
shorter name for polyurethane. In fact, urethane
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.
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
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
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.
– A term used in collectible design and
sculpting, defining fanciful artistic style, a
contrary to precise scaling and representation.
– See pewter.