No, I don't either. But I use natural branches in my cages with their bark and all and I feel as though they may do more to keep nails naturally in shape than fake plastic vines would.
At first I had to buy a leather glove for my Meller's, as she would also draw blood. But now she seems to be much more comfortable with me and I no longer need anything, so building trust with your chameleon can also go a long way.