I would make more parts for kit, had I a small milling machine or metal lathe but lots of parts can be made the old way, by hand tooling, a go slow approach, good measuring tools, files and vices.
For example, metal slipon lens hoods are on my list of future projects, using oak molds and an arbor or hydraulic press.
The mold making out of hardwoods, the roughing out, smoothing and final form can be time consuming, I am no engineer nor machinist, but is part of the fun, collimating into a final product that looks and functions as intended.
Definitely a lot longer process than buying from Heavystar, who sells nice lens shades or elsewhere.
Cheers