Maybe one last thought here. You mentioned milling female moulds for intake tubes. This is a perfect example where precision is critical. Tube require a split mould. So the edges should align perfectly, and the flange surfaces should be straight. At least so good, that you don't need 80grit paper to sand it flush.

Yeh, a good point.

Ive been speaking to a friend of mine today who built his own CNC router with Chinese framework and American/German electronics. He uses it for cutting 10mm aluminium, mostly 2D/2.5D stuff but says he is sure it would do what I'm wanting it to do with ease. Extremely little backlash, doesnt get any chatter or lost steps so long as he keeps to 0.2mm passes and doesnt get impatient with the feeds, and he says it is accurate to 0.1mm as long as everything stays in tune.

So I may go have a play with it sometime, see if we can test it's limitations. He is also currently planning on building a new one, so I may share that build with him and see if we can build something that suits the both of us.

very nice tool, did you use prepreg composites?