Printable Drive Train Module

This is a fully 3D printable drive train module. Students often want to create robots and the like with a 3D printer, but can often find moving parts daunting in the assembly of a robot, particularly a drive train. In order to alleviate this concern, I have created this module, which requires, per module:
2 Case Halves
2 Case Clips (likely edited; more on that later)
4 Basic Axle Attachments (likely 3 edited; more on that later)
2 Sprockets (so-called edited - ignore this)
1 Final Chain Loop
1 Chain Tensioner

None of the above require supports; all fit on a 6" x 6" x 6" (156 mm x 156 mm x 156 mm) print bed. Consistent bridging of 30 mm is required; some strands may need to be clipped otherwise.

Editing of the axle attachments is required to create a functioning module. While this can easily be done (the program Blender can edit .stl files; numerous others can also be used. The circular end has a diameter of 20 mm), the motor that a student may attach could be one of any,