Manufacturing Breakdown

When I made the Hand Tools category, I was thinking of some processes that don't strictly fall into the other categories that exist right now, such as filing and grinding. Admittedly I'm not sure if we need a page for these processes or if we should choose a different name. (maybe Metalworking? that seems too broad...)

As for the categories Emily mentioned (Additive, Sheet Metal, Injection, Composites), I think they make sense.

I also think we should add a PCB or Electronics page.