Needed some luggage tags, designed them using http://thinkandhave.de/personalizer/ and then needed a durable clip to fix them at the cases. This thing consists of an open ring that can be locked with a screw (m3 x 12mm). The model can be changed to other diameters for the ring (change variable ring).
I use two rings, 20mm for the luggagetag and 40mm for the suitcase handle.
Open the model in OpenSCAD, you may change the diameter of the ring. Render and save as STL, then print.
If you like two rings (20mm and 40mm diameter) in one print, then directly print 2clips.stl.
For each ring a screw (preferred m3, 12mm, longer will work too) is needed.