I second the dowels and scrap piece of wood. If you don't want to clamp it down just make some "legs" and attach them to the underside of the piece of scrap wood.

I used an 18" piece of 2x4, 2 1/4" dowels 12" long and fastened 2 pieces of scrap 1x3 18" long to the bottom of the 2x4. I have holes drilled an inch apart 1/2 way through the 2x4. Space the center at 6" then go from there.

15 minutes of your time, unless you have extra money. If you do, send the price of a GP balance machine to me and I will make you a "deluxe" balancer, finsh it in polyurethane (or paint it if you prefer ) and send it to you.