Rigid PVC foam or expanded PVC is a high quality material used for sign construction and craft projects. The methods used to cut rigid PVC foam are similar to cutting standard PVC sheets, and like standard PVC, cutting methods vary depending on the thickness of the material. Thinner sheets of rigid PVC foam require no power tools to produce a sharp clean cut, but thicker materials require power saws with blades designed for cutting plastic.
Lay the sheet of rigid PVC foam flat on the surface of the worktable.
Align the end of the steel rule with the end of the rigid PVC sheet, and mark the distance of the cut with the carpenter's pencil. Make a second mark using the same process. If you are cutting thicker material, skip ahead to step 5.
Turn the steel rule so that one edge of the steel rule is aligned with the two pencil marks you placed on the surface of the rigid PVC foam sheet.
Pull the blade of the utility knife along the aligned edge of the steel rule to cut into the sheet of rigid PVC foam. It may take multiple passes with the utility knife to complete the cut.
Place the 1/4-inch plywood on the worktable, and slide the marked PVC sheet on top of the plywood.
Clamp the PVC foam sheet to the 1/4-inch plywood with the two pairs of self-locking pliers, making sure that the marks you placed on the PVC sheet overhangs the worktable between 1 and 2 inches.
Draw a cut line by aligning the steel rule with the two marks you placed on the PVC foam sheet, and run the carpenter's pencil along the aligned edge to make a cut line on the surface of the sheet.
Remove the steel rule from the surface of the sheet, and put on your safety glasses.
Run the circular saw along the pencil line to cut the thicker rigid PVC sheet.