Summary

Simplistic wall holder.
A bigger and stronger one that holds the spool way more sturdy could be found here https://www.thingiverse.com/thing:5149368

Best to be printed on side to provide as strong "lips" as possible.

Not completely my design. I just (quick and ugly) edited an .stl sent to me in comments by the spool designer with Netfabb and Blender.

I will probably design a better one in the future if no one else makes a better one but it will do for now.