Build by Nonogram
Not a picture. An object.
Most nonograms hide a flat image. This one hides a thing you can pick up. Clues run along all three axes - across, back and up - so no puzzle can be solved from a single face.
Solve it, build it, paint it: every puzzle you finish chips away at a block of stone until a model is left, which you put together piece by piece and paint face by face.
Four sizes, from a 5³ you can finish on a bus to a 20³ that is an evening, and a new object every day.