Bronze silver and gold would be doable. So would masters... but diamond, platinum, and GM wouldn't turn out very well, and even then only the basic hexagonal symbols would work. The symbols are just too complex. Believe me I think they would be really cool, I already mulled that one over but didn't suggest it because they simply won't turn out very good in any sort of limited color process. Even as dye subs they wouldn't come out very good I'm pretty sure.
Basically, nobody is going to want lower league keys, so why bother?