This is an extender/splitter to allow four additional items to be hung from one hook (with the original hook still available for a fifth item). It was originally designed for Command Medium Clear Wire Toggle Hooks, but the model could easily be scaled to accommodate other hooks.

The version with a narrow slot hole is stable on the hook it's designed for, regardless of load balance (see illustrating photo). Other hook dimensions may require tweaking the model's dimensions in order for the narrow-holed extender to fit without tipping. The version with a round hole offers a more universal fit but will become unbalanced if heavier items are hung on one side. 

• Hole dimensions:
  • Slot: 5mm x 2mm
  • Round: 5mm x 5mm
• Total width: 50mm
• Total depth: 12mm
• Each hook width: 4.75mm
• Each hook thickness: 1.80mm

If the model is printed upright, no supports are necessary. (The slot-holed version has one short bridge across the top of the hole.) Your slicer may give a warning about low bed adhesion, but I personally did not need a brim.

I haven't tested the weight capacity of the hooks, but they are only designed for light applications (in my case, holding bottle brushes and measuring spoons). Please reality test for any heavier use, particularly if scaling up.