Starting from unfinished 5/4″ cedar I first planed the board down to ~7/8″:
They were cut into block ~8″ wide and then I could CNC out the center, cut them almost all the way out and run a ball nose bit over the inside edges to smooth:
Here’s a shot at all the various stages:
All 8 were cutout, sanded and treated with Bush Oil:
Final setup with 3d prints from past posts: