Actually what you do is start with a sheet of plywood large enough to handle whatever size panels you anticipate cutting. It sits on two hardwood rails that fit into the slots on the saw top, glued and nailed to the jig with brads. The large piece of hardwood on the back of the jig is set in place using a T-square to make sure it is 90 degrees from the blade, as shown in the photo, clamped in that position and then also screwed and glued to the jig. When the glue is set run the jig across the table, so a slot will be cut right through it. To use just slap the piece being cut atop the jig, resting against the rear brace, and push the jig across the table.