We just built it. No drawings. It is a simple enough piece to just fab up using scrap in the shop. The only critical thing for us was the cores. We initially used a poly core tube from a roll of greenhouse plastic which worked great. When we used that up, we tried white PVC pipe which is more brittle and didn't machine as well. We cut the cores to length on either a horizontal bandsaw - which worked well, but was slow or the tablesaw - much quicker, but a little more dangerous. The notches for the drive pin were cut on the bridgeport.
We just built it. No