My husband, Jason Roberson, supplied us with a box full of wooden triangles, which were cast-offs from a recent carpentry project. The kids painted the triangular "mountains" with tempera paints and then stenciled them with various Birds, Backyard Animals, and Fairies and Elves stencils from Dover. They also stamped onto the "mountains" with a Melissa and Doug stamp kit. We lined up all the creations to make a mini mountain range.
The wooden pieces do not need to be primed for this project. The wood takes the tempera paint and stamping very well. If you want to paint wood pieces to use as a toy, I recommend sealing the wood with melted beeswax after painting and stamping.