I have used the PTFE from McMaster. It is very soft. Once you turn the diameters, just slice it off to length with a good Xacto. Much better than trying to part it off. If you use nylon, use the Delrin, not 6/6 or the like. The Delrin machines mucho betterro.
Of course, if this is all old news to ya, forgive my comments, Big Mike!
The Divot