This is a remix of emmett's famous Gear Bearing. Changes are as follows:
OpenSCAD source is included for manual editing, in case you prefer that over using the customizer.
The STL files include a couple of tolerance variations and different greebles.
Atomic Filament PLA
At low tolerances (under 0.1mm or so), make sure that your slicer keeps the gears cleanly separated. Slic3r PE has a tendency to remove walls between almost-touching elements, Cura doesn't appear to have this issue.