Bicycle back light mount for bike rear racks (with FreeCAD source)

Well, an aluminum part fell off after a few years of use. I can't weld aluminum, but I have a 3D printer, so I designed this plastic replacement. It is attached to a D 10 mm rack tube and fixed with one M3 bolt and nut.

You can edit the FreeCAD model to easily redesign it for other diameters of rack tubes. The model is not parametric because I wanted to make it fast but if you have basic knowledge of FreeCAD you can easily change the following 3 values to customize the model for a different diameter of tubes:

I printed it with PETG. It is very slick. I recommend to smudge the inner parts of the clamp with a rubber glue and let it dry up before installing it on the rack. It will make a kind of rubber layer inside the clamp that will prevent the undesired rotation of the mount around the tube, so you don't have to screw the bolt and nut too hard to fix the mount.

Infill: 15% for the plate, 100% for the clamp. I started 100% infill 1.5 mm below the clamp to enforce its connection with the plate. If you don't want to bother with different infill, you can print the whole mount with 100% infill, but I think it will only add useless redundant weight. The weight of the mount with the settings that I suggest is only 9 grams and this is even less than the weight of the original aluminum plate without the clamp, which is 16 grams…