This spoolholder is my first design ever, and is created to be hung on a shelf. It was created for the @3DPrintingNerd competition. It is wide enough for 2kg spools. The top is slightly curved to follow the curve of the spool, but not completely round so it can still be printed without support.

The bottom has a triangular support so the spoolholder won't break easily, but the triangle isn't too long so that spools won't fit anymore.

The spoolholder was created in tinkercad: https://www.tinkercad.com/things/4rfPkvn3mcA