Inspired by https://kolamtiles.com/, these tiles are made on a CNC router, using a 1/8" bit. The stock should be 12mm thick, and at least 310mm wide by 120mm tall.
First run kolam-24-back.nc, which cuts the holes in the back for 6mmx2mm rare-earth magnets, as well as 4 corner holes for registration. Then flip the piece over, and kolam-24.nc starts out by doing a quick drill on the 4 corner holes, so you can line up the stock correctly on the other side.
Finish the tiles with some sandpaper & stain the tops, and hot glue magents onto the back. Then you're done!