The box top and bottom pieces fit together. Both pieces are carved out of a 3/4" thick piece of wood but the total clearance inside the box is just under 1".
Both pieces will fit on a single piece of 6″×12″ material if you start near the corner and then flip & re-clamp the material between jobs.
I used a 1/8" bit and there’s about 1/16" of wiggle room between the two pieces when the box is closed. If I’d had more patience I would have used a smaller bit for a snugger fit—but each half took about four hours of carving time as it is!
After carving each piece, break the tabs with a chisel and sand the rough sides that cross the grain.