Ikea Ivar Spool Holder - add a pair of 6004 2RS 20MM X 42MM X 12MM (60042RS) bearings, a 20mm dowel, and 8x M3 bolts and nuts. The pins that go into the Ivar uprights are hollowed out to allow M3 bolts and nuts to be fixed to give the part strength. Print 2x (mirror one) to create an elegant spool holder which can be mounted above your 3D printer.