My print in place experiments culminate in this cool treasure chest that has functioning lock (and a separate key that opens it).

After printing, carefully bend the lid and loosen the hinges, breaking any possible z-seam blobs inside. Then check the bottom of the chest and the lock latch; run a fingernail or some other thin part along the latch edges and slightly push apart to loosen any fused z-seams. You can use for example a flat screwdriver and push the latch from the opposite end of the larger gap to loosen it finally. It's better to make sure the latch is free before twisting the key in the lock and possibly breaking it inside.