I established the crossover works well and all the parts have got brackets or screw holes in the right place, so it was time to completely disassemble things and give the case a coat of paint. I used my favourite single coat finish, Black etch primer, good adhesion to tricky surfaces like Aluminium or Zintec, hard wearing, corrosion resistant, good up to 200 deg C and dries to a nice satin finish, what more could you want?