re: CNNP Sheoak Drink Coasters

If you've determined what thickness you want these to be, I'd try taking a piece of plywood and thickness it to desired height. Then get a pencil, mark around your cross section and cut it out with a jigsaw. Clamp down your plywood, Get some double sided carpet tape, tape the cross section down in the hole in the plywood and then level it witha plane and finish with a sander.