I tried to make as many of the parts from scratch as I could, but there were just some that I didn’t think I could do a good version of. For these I turned to the web site ResinParts.com. Keith sells all the R2 greblies you can need. I got them pretty quickly, the quality was excellent and the price isn’t do bad. He has also recently started selling the R5-D4 dome greblies.
Here is a picture of the resin shoulder hubs. If you buy any of these parts be sure to read the instruction on the web site for how to work with them.