Plaster/Paint Mix With Drawing Covered With Wax.
Seeing as how plywood is a stable substrate I used a gesso paint infused with plaster, tinted it and painted it over a piece of top quality birch plywood. After that my daughter and I (who collaborate on many projects) created a lively scene on the painting. We applied a wax coating and scraped away sections to get a peek at the lively scene underneath. This board is 2 feet by 4 feet.