Reply by SnowyRiver

You could just build the sawhorses out of some scrap 2X4, lay the plywood on them and either put some screws in each corner into the sawhorses, or use a clamp to clamp each corner. Another way to do this that makes a good workbench is to put an old solid core door on a couple of saw horses. Its much thicker than plywood and wont sag. You can find old doors that are cheep at recycling centers like Habitat for Humaniity ReStores.

-- Wayne - Plymouth MN