You can use the painted rocks, the plastic markers (use a pencil instead of a pen, it won't fade like the pen), twit and others use old cut up venetian blinds.
Chris uses the plastic markers and paints them black and uses a P-touch for printing the names.
Or these zinc EON markers with P'touch printed labels.
I think that this topic would be great to add to Chris's plant tag thread over in Helpful Hint Forum
The thread "Plant Tags, Labels and Markers" in
Sempervivum forum
Any one that would like to share how they tag/mark their plants here is the link post the this link.
Can't wait to see all the creative ways people idea their plants.