Plaster is a blast to work with. I've tried some different things, like mixing up a batch and pouring it onto a wood substrate. After the plaster is dry, scratching calligraphy and designs onto the surface, then painting with acyrlics. I'll have to find that photo and post it.
Back in April, I took "Plaster Architecture" with Stephanie Lee at Valley Ridge Art Studio. She has done her homework and really knows her stuff. What a fantastic teacher! In class I made a geometric form and a sculpture to hang. I just finished this leaf, it's 18-20" long. Layers of plaster over a wire armature and many layers acrylic paint, the quote was written with a gel pen--the entire piece was sprayed with polyurethane. If you click on the photo, you'll see the rich texture of the plaster, it looks like an encaustic surface. Next I will experiment with wax on top of the plaster. Oh, the possibilities, I could keep myself pretty busy working out ideas, dang day job!