A box that grabs the base with hooks on planetary gears. Unlike most sets of planetary gears, this has no sun gear; instead, a triangle holds the three in place relative to each other.
The lid consists of all pieces except the base. All pins simply pop into place. The base can be printed with no support if your bridging is good enough (I suggest printing it top-down to print the gear teeth correctly). There will be some wobbling of the pins when assembled correctly.
Edit: The pin plate has new pins that are much less wobbly. You should insert them through the lid and then into the gears for easier and nicer-looking assembly, although you can do it either way.