Prusa i3 Single Frame Spool Holder

Another i3 Single Frame Spool Holder

This one attach to the backside of the Z-Axis top mounts using 20mm M3 bolts and nuts and uses 8mm smooth rods on top and sides. I used an old 370 mm smooth rod for the top to hold the spool or 2 spools and cut another one in half for the sides.

Sides can be cut to any length you want, within reason. Threaded rod could be used on the sides but I won't use them on the top.