A tape measure and a square are safe and simple tools that can help kids lay out their pieces for foam and wood projects. Select a tape measure with a longer standout (the distance a tape will stand upright without bending) and clearly legible numbers and markings. A four foot drywall square works well when marking part outlines in large 4-foot by 8-foot foam sheets. Kids will also learn measuring and basic geometry skills in the process.
Almost any bladed tool can be used to cut polystyrene foam. Since safety is a factor, a tool that will cut both foam and wood with minimal injury risk should be the goal. A keyhole, or drywall saw, is a good manual option. It features a round handle grip with a 6- to 8-inch serrated, coarse tooth blade that will easily cut foam and most wood. A jigsaw is a comparatively safe power tool. The reciprocating blade runs through the bottom, so hands are clear at all times. It also has a limited cut speed, since the small blade can only cut so much in one stroke. Kids should not use such a tool without adult supervision.
Once your parts are cut, shaping and sculpting can take place. Small rotary tools, such as those made by Dremel and Rotozip, work well in this category. Use stone grinding wheels, instead of metal cutters, to minimize the injury risk. Hand tools such as rasps, files and sure form grater style planes also work well for sculpting and blocking in both wood and foam. For finishing the surface, a random orbit sander is the tool of choice.
Attaching wood and foam permanently is sometimes a challenge. Specialized foam adhesives are available, but expensive. Avoid aerosols and solvent based construction adhesives, which will dissolve and pit your foam. Use PVA wood glue for a safe and easy alternative. Spread the glue with a paint brush over the surface to be joined. Allow it to dry for 10 to 15 minutes, until it becomes tacky, then clamp the pieces together gently with quick grip style clamps with foam rubber pads on the clamping faces. Latex caulk construction adhesives can also be used.