Often a cap is needed to hide the hex heads of bolts. With this configurable object you can make clip-on caps in whatever color you want.

I include the freecad file which contains a spreadsheet to customize the cap size.

Print in TPU or PETG to give a minimum of flexibility.

Edit: I made an OpenSCAD-File to generate the caps, think it is easier than using the spreadsheet in FreeCAD. As a gimmick, the OpenSCAD-generated caps have their size printed inside. Enjoy.