This is an altered version of the gearbox model available from the ShapwaysMechanical page.
The parts have been perforated in some spots to be slightly more streamlined and also a little cheaper to produce too.
No assembly required, though the middle set of gears must be snapped down into position in order to engage the surrounding gears. I assume this was built into the design to keep larger gaps during the printing process.
2.4 w x
4.242 d x
0.945 w x
1.67 d x