I'm sure it's possible, you'd just need to build a 16/20/24 inch wheel (whichever it is) around a flip flop hub. Chainline issues can be resolved fairly easily.
the real quiestion is why?
then again, if you're just looking for something entertaining to do, and your competent building a wheel, or just want to learn, there shouldn't be any real problem with this. I give it my blessing, assuming you have time and money to spend.
Last edited by fuzz2050; 06-21-09 at 11:14 PM.
Reason: substantive typo