It would help if they were more explicit about the casting methods they are using. The whole article only mentioned casting once in passing, or I would have assumed they were building these parts directly in metal. Aside from having the castings come out, the other main consideration is making it possible for the finishing tools to reach all the surfaces that need polishing, but they said nothing about how they go about finishing these parts.

Andrew Werby
Juxtamorph.com