I use my student copy of Maya, with the script they provided on the wiki. I think if you download sculpty paint or pretty much any other free, sculpt supported program that can import an object you'll be just dandy.
They say they're working on a way to export it, in fact, I think a zscript does exist but it's impractically complicated so it's not really talked about much. But yeah, just use something like milkshape or Wings.