Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:6076394.

This is a hook for this coat rack system that you often find in schools or kindergartens. The design is also compatible with that system especially with relation to the screw caps.

In case you want to improve the design, here is the onshape project. The project does contain a model for the screw caps as well. But I did not try that yet.