This simple product holds work pieces in place and protects their surfaces.
A Bench Cookie™ consists of a plastic disk (3" diameter, 1" thick) with soft high-friction rubber surface layers on both faces. It's as simple as that but it works very, very well. The disks have an excellent grip on flat workpieces. Even sawdust is no problem. They keep projects from slipping while routing, sanding, carving and more. They raise up guitar bodies for edge work and finishing. They make assembly easier and they protect surfaces. And they set up in seconds.
You can make your own. You need ice hockey pucks and soft rubber disks but finding the right kind of soft rubber could be a problem. You can buy the correct high friction rubber material from Lee Valley
There's not much to say. This is a really useful product that simply works. Highly recommended.
Manufacturer link: Rockler.com
CLARIFICATION. I don't have any relationship with the manufacturer and bought the product at a regular price for my own use.