This is a spool holder meant to attach to inexpensive rack shelving found just about anywhere. It slips over the outermost edge and has a hole to insert one M3 screw to prevent the spool from falling off.
Note that if you attach many heavy spools to the top, your shelving can tip over if not secured to a wall, or otherwise made bottom-heavy.
rackShelvingSpoolHolder.STL | 12.4KB |