Backdated Oct 16th, 2016:

All the required 3D printed parts have been finished! The image below shows all 7:

The two parts of each drum fit together loosely and will have to be shimmed with some tape before being glued. The holes are sized for M3 or 3/16" rod. The large openings (visible on pt 2 of each drum, hidden on the underside of pt 1) are sized for 603 bearings. I was only able to find 3/16" rod which won't fit through my bearings so I ended up leaving them out. The PLA I printed these parts out of is slippery enough that they move freely on the smooth brass rod without bearings.

I also started on the 2D design for the arms and supports that will hold the printed parts.

You can see the overhead projections of the drums in red, along with top views of the wooden supports. White lines represent parts to be cut.