Puzzle Drawers

With the lower drawers and the cross-shaped piece installed, we come to the upper level:

The left-hand ratchet tooth is now engaged with its sawtooth rack, and the large plate from the right-hand lower drawer is aligned with the hole in the left-hand shelf. We also see the other key mechanism inside the chest: when the lower-right drawer is pulled out about halfway, the lumpy part on the large plastic plate raises the gear up so that it no longer engages with the toothed racks of the upper drawers. The left-hand upper drawer has a plastic lump on it similar to the one on the right-hand lower drawer, to disengage the left-hand ratchet tooth:

We now come to closing the lid.

Source: incoherency.co.uk