There are many ways to support the plywood when you cut it, sawhorses, other pieces of wood or at the edge of a table. It’s important to support the whole piece of plywood when you’re cutting.

This modular, expanding workbench / workstation is made of 2x4's and plywood and doesn't take too much space is your garage or workshop, then when it's time to use, just grab a sawhorse and extend ...