Each arm is only an inch wide, but cross cutting an inch wide piece of plywood is, of course, very dangerous, so I made it 6″ wide. Each piece will be cut after the groove is cut on the backside, as well as each hole is made in the center. We’ll then epoxy a 3/32″ wood insert into the hole and the #6-32 x 1″ screw to either a knurled thumb knob or a wing nut. Of course, if you just want to use a screwdriver to screw the screw in each time, you don’t need to add a knob or wing nut.