Since Ben said that he isn't making them anymore, I thought I'd try my hand at it.
I bought a precision metal lathe, a short shifter and some bearings.
The main shaft has a roller bearing and the others have 2 SKF ball bearings each for stability (6801Z, 21mm x 12mm x 5mm).
At about $8 each, they are a bit pricey, but I didn't want to cheap out and end up with something with excessive play or that would fall apart after little use.
They are butter smooth!
The small shafts must be turned down to 12mm. I suggest stopping at 12.1mm and test fitting. You can then finish off with fine grit sandpaper and polish for a tight and smooth fit.
The cups need to be widened to 21mm, but I stopped at 20.9 for a tight press fit. I did this so that the bearings could be semi-permanently mounted in the cups and the shafts can slide into them. The bearings can still be driven out of the cups using the bolt at the rear in case they ever need replacing, but they should outlast the car.
Fun stuff!
