Pen holder for Gondola for polargraph/hanging v pl

This is the pen holder for my lightweight polargraph/hanging v plotter gondola.

For the full set of parts, you will need the following printed parts:

1 x Gondola

1 x single arm

1 x double arm

1 x weight arm

1 x pen collar

1 x pen holder (the pen holder is designed to be a press fit for quick pen changes so you can order one or more of these)

You will also need 1 x M3x12 pan head screw for the pen holder and optionally, a long M4 screw with a large M4 washer, as many M4 nuts as you can thread onto the screw and some 608 size skate bearings for weights (you don't have to stick with these as weights but they work for me).