Stormpath made a run of replica transistors with threaded rods in sizes that fit both Roman's and Parks clamp spacers. (Parks was actually part of the gear assembly..) Maybe Stormpath has some left.

I guess the transistors and washers on the original prop were glued on.
Otherwise, the transistors can be found in some old electronics or in stores specializing in obsolete components.
I don't think anyone has found perfect washers. I think they could have been adapters for M8 countersunk screws. I have also found some M7 washers that looked close, but never M8.
Ob1kenny did have some aluminum washers for sale earlier. Those are what I use.
Edit: Stormpath is the guy with the Panda avatar.
Be careful if you drill out real transistors. Clamp them in a piece of wood with a transistor-shaped hole, so that you don't sqash them. Drill slowly and not too far.