Under-shelf bracket for 3KG spools. I used a spool core from Spannerhand's drybox, and extended it to 100mm. Using some 8mm thread, 4x 608 bearings, and a few washers, it holds either a 3KG spool, or 2x 1KG spools nicely.

Print with the longest spine on the bed, and the print will work fine without supports for the hook end.