I didn't have a whole 2x4 laying around so I cut these 4 2' pieces from what I had.

I squared up the edges in my bench top planar.

I further ripped those down into 8 pieces.

I ripped those 8 pieces into 16 pieces. 

I glued up 2 panels from the 16 strips and evened them up in my planar. I cut one in half and squared all of the edges with a miter saw. Final dimensions 10.5" x 20" and 10.5" x 10.5" about 0.5" thick.

I sketched images on the panels with pencil.

I cut the images out on a scroll saw.

I stained them using an even mix of Varathane barn red and navy worn with a light top coat of Helmsman satin spar urethane.