This past summer my friend Sharon and I collected some flat rocks to use to draw zentangles. I traced the rock into my small sketch journal and then drew my design in that shape. I wanted to practice the design before I drew it on the rock. I coloured it in with markers.
Here is a picture of the rock and journal. I put a micron marker in the picture as a size comparison. I still haven't drawn the design on the rock yet! I'll have to try it soon.