Basics of Building Plastic
by Richard Schumacher and Venita Lake
photos by Richard Schumacher
Originally presented as a clinic at the Long Beach NMRA
Plastic structures offer a wide variety of building
styles at very affordable prices, and they continue to
improve in quality and detail.
Instructions for simple plastic structures by
manufacturers such as Design Preservation Models (DPM),
Smalltown USA, Atlas, and International Hobby
Corporation (IHC) range from overly simple to very
helpful. Those in recently developed kits seem to be
more comprehensive. Following the basic directions (trim
the pieces, glue them together, paint if you wish, and
add the windows) will probably produce a pretty good
structure. A better building can be made, however, by
planning ahead, using the right tools and supplies, and
The building assembly described here is for a DPM
(Design Preservation Models) "Kelly's Saloon",
kit #101. This is an inexpensive but very nice kit,
highly recommended as a beginner's structure project.
We have also added online construction articles with
lots of color photos for a different DPM structure and a RIX Smalltown USA structure
which use the same techniques explained in this article.
To begin building any structure, first review the
directions, any diagrams, and the parts of the kit.
Visualize how the pieces will go together and how you
wish to paint them. Consider ways you might
individualize your building.
Useful tools include an x-acto knife, scissors,
tweezers, files, side-cutting pliers, and 100-grit
All major pieces must be prepared before gluing and
painting. DPM and Smalltown USA structures usually have
four side walls, roof materials (a sheet of plastic for
the roof and small plastic brace strips), and small
details such as chimney pieces.
Determine how sides will be glued together. Most
structures butt an edge of one piece to the back of an
adjoining wall. Since edges are usually slightly beveled
to facilitate removal from the manufacturing molds, they
must be sanded square. This is an important step for
kits with this type of corner construction as it
prevents assembly problems and a very visible and
If your kit uses this type of corner assembly,
smoothly sand off the bevel, test fitting to ensure the
edge is square. Many kits are designed to fit together
without the need for this sanding, so you need to
carefully look at the edge and do the "gap
test" (above) to determine if sanding is
required. For those kits that will need the
sanding (such as DPM and Smalltown USA), note that one
edge usually is plain (for glue) and the other has
molded-in detail. Donít sand off the detailed edge!
The back sides of the walls should also be sanded on
a flat surface to clean up window openings and assure a
good fit, without gaps at the corners or window panes.
Casting tabs at the wall bottoms, and small pieces
molded together on sprues, may be cut with small nippers
or an x-acto knife. The sandpaper technique is used to
smooth the wall bottoms. Very small pieces may be left
on the sprues until they are painted and touched up.
Where a surface will remain unpainted, small parts can
be placed on masking tape, sticky side up, for painting
and security until they are needed.
Some pieces may have dimples or holes on the back as
a result of the molding process. These should be filled
with carpenterís wood filler or Squadron green putty
if they are visible above the roof line or if the
building will be lighted. When the filler has completely
dried, it is sanded smooth. More than one application
may be necessary for larger holes as these fillers can
shrink as they dry.
When all pieces fit accurately, they are ready to be
glued. Liquid styrene glue such as Testorís, Tenax or
Plastruct bonds the plastic by melting the two pieces
together. Donít use tube-type plastic glues. The
liquid glue is applied with a small brush or a needle
applicator. Coat the two surfaces (edges) to be glued,
and while still wet firmly squeeze together. This
technique ensures a solid bond. After it starts to set,
go back and apply additional liquid glue on the inside
of the joint, which will wick into the joint. Do this
sparingly to avoid glue running to the outside and
etching the brickwork details.
Assemble the four walls first. You usually start with
the front wall and one side. Then attach the other side
wall, and finally the back wall. On many of these kits
the back wall installs between the two side walls.
At this point attach the other half of the chimney
pieces, if your kit has part of the chimney molded into
the side wall (like the kit in the photo above). Make
sure to sand flush the bottom of the chimney pieces
before gluing them in place or the roof will not fit
After the wall joints are thoroughly dried, the roof
is fitted. Many of these kits have a styrene sheet roof
which must be cut to fit. You may wish to cut a test
roof from cardboard before cutting the styrene. Some
kits will fit the roof in from the bottom against the
base of the chimneys (see the photo below); others may
provide styrene strips which are to be cut and glued as
a shelf for the roof to rest on. Scissors work best to
cut and trim the plastic styrene roof material. The roof
and supporting strips are assembled with liquid styrene
One way to improve the appearance of the structure is
to add holes to the chimney tops. Three ways include
drilling a round hole (which is the hardest method),
slicing a section of Plastruct square rod (which has a
built-in round hole in the middle) and gluing it on top
of the chimney, or attaching a small slice of brass
tubing. Youíll need to sand the top of the chimney
level before using any of these methods.
When the glue sets, rub the base of the entire
assembled structure on the sandpaper atop a flat surface
to assure that the bottoms of all walls are even. This
provides a solid bond with the ground when the building
is installed on your layout.
If the kit has recessed doors or windows, trim the
casting tabs or excess material and assemble the bay as
a unit, carefully checking the fit into the structure
before the glue totally sets.
On this structure, the recessed door has been
improved by adding a ceiling at the top of the door bay
from a surplus piece of the roof styrene. The styrene is
attached flush with the front of the door unit, so it
fits inside the building. After the door assembly dries,
glue it into the door opening.
If the doors and windows are separate pieces in your
kit, donít glue them in yet. Youíll want to paint
the building and windows separately and then glue them
together. Our example kit has the doors and windows as
part of the walls.
Before painting, wash the entire building using
dishwashing detergent to remove sanding residue and
finger oils. Rinse with plain water and air-dry
thoroughly. This ensures that the paint will bond
properly, and will prevent paint blemishes caused by
finger and casting oils on the plastic.
Plastic structures are painted with a water-based or
latex paint such as Badgerís Model-Flex.
These, as well as craft paints, may be brushed or
airbrushed on your model. Craft paints are available in
colors other than the standard railroad colors which may
be more appropriate for buildings.
Paint the inside of your building a dark color to
prevent an unnatural glow in lighted buildings or
buildings with large windows. You can go back and paint
it a lighter color or "wallpaper" the interior
if black or dark brown is too visible through the
windows. The example building was painted tuscan oxide
red, which is a good brick color. This red is dark
enough to use to paint the interior as well.
After painting the interior, paint the entire
exterior, including the roof, your brick color to ensure
the building has an even base color coating. When you
look at any structure, you see the paint. The quality
and detail of the paint job makes the difference between
a toy building and a scale structure.
Brickwork is enhanced by additional attention to
detail. Brick masons add texture to brickwork by laying
a contrasting or darker color of brick in random or
carefully-planned patterns, especially on the front of
buildings. This is duplicated by brushing on a
contrasting color paint on individual bricks or coloring
them with a fine-point art marker, such as a Berol
Prismacolor marker. The Berol mahogany red color is a
good contrast to the tuscan oxide red base brick color.
This "freckle" technique is a good television
Mortar is an essential detail for brick buildings. It
makes the brick detail stand out. Two buildings may have
the same color of brick but look very different because
they have different mortar colors. Commercial products
like Robertís brick mortar come in a variety of
colors. They are applied and then wiped off so that the
color remains only in the joints. Art hobby acrylics,
such as Ceramcoat by Delta, are available at craft
stores. Off-white, sand, light earth and gray colors are
all appropriate for mortar. Coloring the mortar makes a
big difference even if you choose to keep the original
color of the plastic model and not paint the walls.
Q-tips help when wiping the mortar from the small
"nooks and crannies".
After the mortar dries, mask around the windows and
paint the smaller areas like window frames or
"stone" window sills in contrasting colors.
Scotch tape works very well for most masking tasks. Very
small brushes may be used to hand paint these details.
More expensive kits have the doors, windows and window
sills as separate pieces, making them easier to paint
and then attach to the structure after weathering.
Add signs representing those that are painted or
papered on the structure. Dry-transfer signs, like those
from Woodland Scenics, are usually easier to apply than
decals. Purchasing and using the burnishing tool for
dry-transfers makes them easier to apply as well. The
signs are applied before the weathering, as the signs
are weathered too.
Weathering with colored chalk or copier toner is the
quickest method. Apply it vertically, as rain pours
down. Sticks of colored art chalks are available in
boxed sets of "earth" colors, rub some chalk
off the stick with a stiff brush and apply to the
building. The chalk or toner needs to be fixed in placed
with Dullcoat or cheap lacquer hair spray. A final bit
of detail painting on the trim, perhaps in gold or
brass, will give a hint as to the era or level of
maintenance for that corner store.
Since we usually are looking down at model
structures, pay careful attention to roof finish and
details. Flat roofs may be covered with tar paper
composed of tissue paper cut in strips or
"rolls" and affixed with grimy black paint.
Seams or the splash onto the wall may be done with super
glossy black paint. Or a roof might be painted black or
brown and dusted with a fine talc powder or very fine
ballast or sand to replicate a graveled surface. A fine
sandpaper, perhaps the same piece used to sand the
walls, can be cut and glued down. Detail chimneys,
giving thought to where they would logically be in the
roof, and drilling out the flues and painting them
black. Add trap doors, sky lights, vents, or puddles.
The building on the left has glossy black tar lines
hand painted onto a matte gray roof. Fine ballast was
bonded to the roof on the structure at right to simulate
a gravel surface.
Structures without clear window glazing donít
"look right". The glazing reflects the
surrounding environment, like real glass, and adds other
texture to the structure. Notice the difference glazing
makes on the example on the right.
Install the window glazing after the painting and
weathering is complete. Make sure the vapors from the
glue you use can escape the structure, or it may fog the
glazing material. Some modelers attach their glazing
with white glue to avoid this problem. Stores with
larger windows should have signs or something on the
interior so that they do not look vacant. If colored
"wallpaper" or small pictures from a magazine
or paper curtains or window shades are used, the
building will seem to be occupied. Masking tape may be
applied to the inside of the second story windows to
simulate window shades. The masking tape is self
sticking, an appropriate color, and easily applied at
various heights. A color or laser printer can print
window signs on clear overhead transparency sheets,
making custom storefront windows.
Cardstock inserted inside the structure will block
light from passing from one side to the other. Use black
construction paper, or paint the cardstock black. This
prevents the usual unrealistic "see through"
effect, as if there were no walls or floors inside the
building. The added darkness of the interior will also
enhance the reflections in the window glazing, and hide
the fact thereís no furniture or equipment inside.
The sign sticking out from the front of this building
adds more texture and interest. Waltherís sells an
inexpensive set of these signs, including the signs and
matching decal lettering. Blair Line and JL Innovative
Design also offer plastic and paper structure signs.
Although painting and weathering takes some time, all
of the additional detail steps produce a finish
drastically improved from an unpainted plastic model or
one with just a "one color" paint job. Use
your imagination and have fun thinking of ways to set
your plastic structure apart from the rest. Signs,
people and animals, boxes and barrels, and even more
roof detail will further enhance your model. Add
furniture and fixtures behind large windows to amaze the