I made up a wall mounted spool shelf.  The brackets have a ¾ end for a piece of pipe or a wood rod. I didn't have anything in front of me at time of design so I also made an adapter for ½ pvc pipe that I found at work, it sags a little at 2ft span but seems to work good. The brackets I did in pla at .2 height. the pipe adapter I did in petg for a stronger layer bond with 3 walls. It's designed to fit on the mini bed since that's the only machine I have.

Hope you enjoy.