A quick perusal of the web seems to show me 45B as a press camera, not a monorail like the graphic view. Check this out It seems to me the question on 4x4 boards is usually whether they have a rolled edge flange, like the later Pacemaker boards or Busch boards, or are flat with, or without a light trap. The last are easy to copy in masonite or, as you have, aluminum. Without a rolled edge, 4x4 is 4x4 is 4x4... what could be different?