Hi William - Its the outside skins of things that do the work. So a stiff outer is needed say CF offcuts, But to have CF offcuts on the inside is a waste of material and extra cost so you either make hollow parts ( hollow parts may vibrate) or you fill the skin with something eg sawdust, sand etc. You will also need mass as its a mill, so perhaps the "core" is heavy such as steel swarf. Once you get the design rolling then you will need to do some inertia studies to figure out motor sizes. I don't think you should use N34 motors N24 or N23 will be heaps. But that will come out in the wash.

Re infusion: water is the enemy and its not discussed or understood much in infusion processes. The people that know don't share much as they have industrial processes tied up so things like vacuum soaking is not discussed much.... Infusion videos make it look very easy but like all skills and processes there are traps and tricks...If you read up on vacuum soaking air conditioning systems to flash off oil and impurities in the system this will give you some idea of what your up against. Peter

By the way precision C7 does not exist. C7 is C7 and it has a spec. Precision in machines tools is a long way from C7...