Circular saw jig
While I don’t care for wrestling sheet goods atop my tablesaw to cut them, I dislike even more the hassle that comes with setting up most circular–saw guides: all that measuring, offsetting, and praying it comes out right. So I built this simple tracked guide that puts the blade in line with the cutline every time.
But my favorite for cutting sheet goods is a sheet of thick rigid foam insulation. Just lay the plywood piece on the foam, and start cutting. The foam will support the plywood and you can cut into the top of the foam (as opposed to the top of your work table) -Tips to Cutting Plywood with a Circular Saw | Ana White