The folding doors like in an old-time tramway or trolley bus. For the real door enthusiasts ;) The doors from both sides are open and closed by using one of the levers:
It is designed to be print-in-place.
On Creality Ender 2 with Slic3r PE, I think these are the settings that are important (assuming that the basic temperature and extrusion calibration is already done):
0.2mm layer height
External perimeters: 70%
XY separation of supports: 70%
It is printable in one piece. Print with supports, oriented like in the screenshot. The mechanism requires a bit of help to get going. Expect a few gear teeth to require help of a craft knife or a needle file.
Uses gear.scad 1.1 by Leemon Baird.