(quoted, in silicon)
as much as i would love that, creating expansion boards from scratch, using copyrighted diagrams, or to be accurate, source chips that aren't generic:
1, serious industrial equipment for pcb's on that detail and scale. (cad and robotics knowledge are highly recommended, i'm in baby steps...no i'm not, i'm an egg.)
2, accurate 1/1 parts.
mirror chip clones would work if the layouts were identical.
...
to build amiga expansion card, FROM SCRATCH is nothing short of matrix like skills, and resources.
...
yeah!
of course, i's LOVE to see what the next post on this specific subject will be...
[edit]
a chance with a500 perhaps, and that's really stretching it.
anything higher is from factory grade equipment. (not like the a500 card wasn't anyway.)