I covered the surface with paper and tape to create an organic feel to the environment. Following that, I covered the paper with papier-mache that I have made with toilet paper, glue and water. Left it to dry for the night.
On the following day, I colored it with acrylic paint. Then I sprayed a mix of water and glue in order to create a base for the dirt to stick.
Here is a top view of the arena:
I invited two of my friends (Alex and Jackie) to test the arena. I recorded their feedback and it was extremely helpful.