I found these really thin mechanical pencils. They work well enough but are too slim to be comfortable for extended use. I got a few thinking I’ll see if I can do an overlay for them.
This is my experimental effort with the shortest of the three I got. The overlay is Bamboo shaped with a knife. The carving is done with a Dremel tool. I wasn’t sure how easy or hard carving in Bamboo would be (its pretty hard to control well!) and how the various cutters would react to the material.