This rocker jig is built from gas spring parts. A gas spring is what holds the hatch open on your car.
The white channel is from the shelving found in your bedroom closet. The bungee adds stability prior to tightening the wing nuts.
Click this photo for details on the exact parts to buy and the cost. I used www.mcmaster.com to get my gas spring parts.
http://ncpaddlesurfer.blogspot.com/2007/12/rocker-jig.html Here is my old rocker jig based on a popular design found on the web. It's OK for goofing around, but is useless for serious work.
My new rocker jig locks down secure and precise. I can map the exact profile of a rocker.
Happy SUP Summer
22 hours ago