Thought it was wood initially

It's anti fatigue foam mat. I used a wood burning tool to cut in and make the illusion of planks and to hide one of the joinet where two sheets came together. Then I dragged it to make lighter grain striations. The paint job for the wood is burnt umber undercoat and then a dry brush mix of yellow oxide and burnt sienna.

This reminds me to load up the second shield I made!