Only caveat being don't do forks to start with. Fork failures are nasty, and especially don't do disc forks, as the loading forces are that much greater in some aspects.
How you planning in doing it? Do you have any fab experience? Worked out whether your chosen brake is going to clear folding mech etc? See the stuff Ben cooper from kinetics does to bromptons?
Only caveat being don't do forks to start with. Fork failures are nasty, and especially don't do disc forks, as the loading forces are that much greater in some aspects.