Add storage to you marble run - Holds up to 10 marbles.
Simply remove the knob as pictured.
Slide the holder over the threads while ensuring the back edge fits under the gear - If you slide the back edge under the gear at a 45 degree angle, there is no need to remove the gear for this step.
Once properly seated, reinstall the knob.
Print Settings
Supports required
The filaments used in the pictures above: