How to Trim & Smooth Styrofoam

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Things You'll Need

  • Old candle

  • Serrated knife, craft knife or electric carving knife

  • Ruler

  • Permanent marking pen or ball-point pen

Styrofoam is a wonderful base for many craft projects. It is available in varying sizes of ball and cone shapes, assorted thicknesses of foam sheets and several die cut shapes. Trimming and smoothing cut Styrofoam pieces will allow you to create your own shapes and craft projects. The trimmed and smoothed edges will create a sanded edge for your finished project or a straight and fitted edge for attaching other Styrofoam pieces. Most of the tools needed for trimming and smoothing Styrofoam are ordinary household items, making this an easy and inexpensive process.

Cutting And Trimming Styrofoam

Step 1

Rub an old wax candle along the blade of a serrated knife, craft knife or electric carving knife. This will allow the blade of your cutting knife to slide easily into and through the Styrofoam.

Step 2

Measure and mark your cutting line on the foam with a permanent marking pen or by pressing an indentation into the foam with a ball-point pen.

Step 3

Cut and trim along the marked line with a waxed cutting blade. Use small strokes and short sawing motions. Do not force the blades, this may cause the Styrofoam to crack and break.

Sanding And Smoothing Styrofoam

Step 1

Cut or trim your Styrofoam project pieces.

Step 2

Cut a 2-inch square scrap piece of Styrofoam. Rub the cut edge of the scrap piece against the cut edges of the Styrofoam project pieces. This will sand and smooth the rough-cut edges.

Step 3

Rub the scrap piece of Styrofoam against sharp corner edges of the cut Styrofoam project pieces to round, blend, taper and shape them.


For larger Styrofoam projects, use a waxed hacksaw blade to cut and trim the foam.