This is a clip for mounting a tail light onto a bike rack. I used it to mount a "Portland Design Works" Danger Zone tail light to my "Topeak" Super Tourist DX bike rack. This design will hold many different tail lights as this clip design seems to be standard among some manufactures. I have tested it with a very cheep Chinese light and it works well for that as well as my Danger Zone light. It should also also work with "Planet Bike" lights. The rack mount holes on this clip are 50mm apart. I have included a base clip that can be adjusted in Sketchup as needed for different designs. This is not a useful design in itself, its just for building other sizes as needed. This is more or less a copy of http://www.thingiverse.com/thing:8947. I don't know OpenSCAD so I redesigned it from scratch in Sketchup. The above rack mount clip works great but the bolt holes at 81.5mm were two far apart. if you need a bigger clip or want an OpenSCAD file for this clip try the above link If you need a single hole mount You might find http://www.thingiverse.com/thing:25621 helpful, but I found the design good but the measurements to be way out of whack and measuring in meters not millimeters. I printed this with ABS to give the flexibility and strength. I would not recommend PLA as the clip needs to flex and the mount would not hold up in the elements on the back of a bike as well.