just 6061. it has to be a nice slight press fit, and dead square, which isnt easy on the best of machines using multiple setups.
im eyeballing a cheap as chips brother and my mesa kit today... haha. if i could make it run with no significant extra dollars input within a week or 2... it would be worth it, but as i know from my Maho, it could quickly become a nightmare that wont be useful any time soon. of course, the brother is barely more sophisticated than the novakon, so it could never be *that* bad.