I have a bike lock that mounts to the seat stay by clamping around the tube and it’s never quite fit right. I can tighten it all I want but the plastic on metal doesn’t really prevent it from rotating slightly. It’s not a huge deal but it’s enough to bother me.
In the past I had a GPS handlebar mount and it came with a little piece of rubber to help shim it tight and grip the bar which prevented it from rotating. I didn’t have any random pieces of rubber around, but I do have flexible filament! TPU (or Thermoplastic PolyUrethane) is 3D printing filament that is sort of soft and flexible, so I loaded it up in the Prusa MINI+ and designed a piece in OpenSCAD.
When I say “designed” there is barely a design, as it’s just a hollowed cylinder with a slit down the side. While 3D printed parts can be complex, they can also be really simple. (I once printed a shim!)
Again, for me it’s all about solving problems. I could have hunted around for a piece of rubber, or ordered some, but I had the filament on-hand, I can design things quickly, and they can print while I do more important work.