Thanks for this fascinating foray into the future of DIY car culture. However, just as in 3D printing, so too in grammar and punctuation, the key to everything is precision. For instance, is the sentence “Porsche, for example, uses laser-sintered powder deposition to make hard metal parts, that are no longer otherwise available, for the 959 supercar.” actually meant to convey the idea that NO hard metal parts AT ALL are now available from Porsche for the 959? Punctuated as it is, that is what it means (restrictive clause between commas). If the idea is that Porsche will print such parts as are no longer available, just remove the commas after ‘parts’ and ‘available’.