I just converted my cheap Epiphone to semi-fretless (5th string and up), and I love it. I did it using a brass sheet about the same thickness as my frets.
I'm definitely not a super good player- I have about 10 months experience on the banjo and several years on guitar and mandolin. To folks who are nervous about going fretless- don't be. As long as you are playing single notes or two finger chords, there's really not much of a big difference. Playing with your nails on your first three fingers is a bit of a change, and is hardest with your ring finger and easiest with your pointer. I also had to completely stop using my pinky, which was easy because I also had to stop using 3 and four finger chords- the times when I fretted single notes with my pinky was usually just for economy of motion and not out of necessity.
All-in-all, I think it was a great decision and I don't see myself going back.