He wanted something different on the belt drive so he split the 3 in. primary belt and used a 3/8th round cutter in the lathe to cut a groove in the pulleys. For the outer plates he stretched round stock over an oxygen tank to get a round look to it, then drilled holes in them for insulation. The nuts and bolts are all tie-wired or carter pined.
Canon EOS-1D Mark II, f/9 @ 17 mm, 1/160, ISO 200, No Flash