Ebbie, you can see two examples of my designs burned on tagua slices (one of holly, one of a wolf) at our (still unfinished) website
and an enlargement of the wolf piece at this address. The wolf about one and 1/8 inches wide and 1 and 3/4 inches tall, including the dark rim which is the outside coating of the nut.

The holly was painted with acrylics, the wolf was colored with oil pencils. Both have a coat of Deft lacquer.

Tagua is harder to burn than wood but you can get really crisp detail. I like to carve the details into the nut with the burning pen. They have a beautiful shimmer when they're done.

At craft shows I have a small sign that explains about tagua and where it comes from, and I keep some unburned slices and a whole tagua nut or two. Once in a while I end up giving away my samples to someone, for example a schoolteacher who is teaching a unit on Central America and wants to show them to the kids. Also once in a while someone comes up to the booth to tell us about how they had taguas in their homeland. One woman (from Ecuador? Guatemala? I don't remember and my understanding of the geographical distributions of tagua is pretty scant) said that as a kid she had doll furniture carved out of taguas.