Tips for Modeling With Styrene Plastic

Vibrant colorful pieces of tiny bits of plastic

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Styrene plastic (more formally known as polystyrene) is one of the primary materials used for scratch-building models today. This plastic is easy to cut and glue, comes in many thicknesses, and is even available in custom shapes and textured panels.

First-time modelers are often scared away from scratch-building. If you aren't used to working with plastic, the idea of creating a model freehand, without the benefit of a kit can be intimidating. But styrene is actually very easy to use. After a little practice, you may find you can construct a model building from scratch almost as quickly as you can when using a kit.

Tools and Materials Needed

Scratch-building doesn't really require a lot of fancy tools, although there are many gadgets out there that can make the job easier. The basics you need to get started can be found at any hobby shop for about $10 or less.

  • Hobby knife: Always use a fresh, sharp blade.
  • Scale ruler: This is the perfect tool for making precise measurements and straight cuts.
  • Sharp pencil: This is the best tool for marking styrene for cutting.
  • Glue: An adhesive designed specifically for styrene will yield much better results.
  • Sandpaper: Keep a variety of fine grits on hand.
  • Compass or French curve: This tool is required only when you are cutting curves or circles. 
  • 01 of 04

    Marking Your Cuts

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    The most important part of cutting styrene doesn't involve a knife. As with any material, the secret to perfect cuts is good measurement and planning.

    Lay out your cuts with a scale ruler, and double-check each measurement. Most rulers will not put the "0" mark precisely on the edge, in order to preserve a clean measurement. Always use the markings, not the edge of the ruler, to make your cutting marks.

    Use a sharp pencil to lay out marks on the styrene. Since most styrene products are white, marks are easy to see.

    A compass or French Curve can be used to lay out curved lines.

    Continue to 2 of 4 below.
  • 02 of 04

    Cutting Styrene

    Exacto knive
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    Once the marks have been made, it's time to get cutting. Depending on the thickness of the styrene, you may be able to cut completely through in one or two passes, but the basic best practices are all the same:

    1. Mount a new, sharp blade in your hobby knife. A fresh blade can make all the difference.
    2. Align a metal straightedge along the cutting line. The scale ruler can serve well for this purpose, but make sure to use the edge on the side opposite the measurements you normally use, in order to prevent damage to the edge and scratches to the measurement markings.
    3. Hold the straightedge firmly as a guide, and begin with a very light pass of the knife along the side of the straightedge. This will give the blade a path to follow as you increase the pressure in subsequent passes.
    4. Make additional passes at a slightly greater pressure to score the styrene. The pressure should still be fairly light, and make sure not to force the cut, which can cause the blade to go astray.
    5. Unless you are cutting very thin (.010 or less) styrene, you probably won't cut completely through the styrene. This is fine; just make three or four light passes to score the plastic, then move to the next step.  
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  • 03 of 04

    Snap the Styrene

    Cutting with knife
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    If you're working with thicker styrene, you won't cut completely through it with the hobby knife. Fortunately, you don't have to. The next step is to snap the styrene board. If you've ever worked with drywall, this procedure will look very familiar.  

    After scoring the styrene with light passes of the hobby knife, you can bend the styrene away from the score to snap it cleanly along the line.

    A second snap in the opposite direction may cause the pieces to separate completely, or you hold the styrene piece bent at an angle, then use the hobby knife to cut a clean line along the backside at the scoreline.


    • When making multiple cuts on plastic, it is often easier to make several small cuts, taking off each piece one by one.
    • For windows and doors, you may need to cut all the way through on two or more sides. Often a little gentle flexing will help snap even these smaller areas without damaging the rest of the wall.
    • If you are making walls from a larger sheet of styrene, remove the window and door openings before cutting out the walls themselves.
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  • 04 of 04

    Sand the Cut Edges

    styrene sand
    Ryan C Kunkle

    Once the cut is complete, finish the edge with a quick swipe or two across the cut edge with some fine-grit sandpaper. Emory boards, sanding blocks, or sanding ribbons also work well.

    When sanding, make sure to keep the cut square (unless you are trying to get a beveled edge.) As you learn and are honing your skills, it is often easier to cut a little long and then sand to an even finish. As your measuring and cutting skills improve, you will learn to cut more precisely and less sanding will be needed. 

    • Tip: A heavy-grit sandpaper can be used to scratch a rough surface on the plastic. This can be useful if you want to create a simulated wood grain or other effects.

    With your pieces cut, a styrene solvent glue will make quick work of assembling the model, just as you do when building from a plastic kit.