Balayage board with curve to rest snugly on the contour of one's head.
I designed it in a small form-factor to fit my 220x220x220 build volume. I printed it upright with a giant raft to adhere to the bed properly. If you print it laying down, the supports may be somewhat difficult to remove and the finish will be pretty jagged (depending on layer height).
If printing upright, add a >10mm raft for it to adhere properly.