Because we all have something to clip but the clip never has the correct size..

This is an openscad file to generate a clip that fits any cylinder.
Adjust the innerWidth to fit the thing(s) you want to clip, adjust thickness (the more thick the more rigid) adjust height to increase grip.
Print support provided

You can increase the base width to improve printability, adjust height to match your printer layer height, default value .3
Example

clip_9_3_15.stl is an example of small clip that i made to prevent my shower to slip down (temp solution)
Inner radius is 9mm fits my shower bar
3mm thickness give a good rigidity
15mm height to have enough grip to the bar
it clips easily and fits well