WOW man that is an amazing workshop you got there!! Do you use it for work related stuff or just straight 'man cave' hobby use??

Oh and i noticed your printing directly on the PCB, generally PCB arn't known to the as flattest especially compared to the toolsteel sheet your using underneath. copper and fibreglass have different rates of expansion, maybe try a plate of glass on top if have flatness issues

I'm just prowling the internet for knowledge and awaiting for all my parts to arrive, i'm building a Sells mendel =)