A trick I learned from a plastics worker was to pass the flame from a propane torch over the cut edge. Pass the flame back and forth at a moderate pace. The rough cut edge will soften and smooth right out, giving it a polished appearance.
Try it out on the cut off piece first, of course. And do it outside while you're at it - while it is possible to ignite the stuff, even melting it generates some horrendous odors!
Brian