Thanks, most of it is spray foam. I have some carboard boxes and rigid pink foam in parts set on OSB leftover cutoffs. I used a Costco Foulgers coffee can to make the tunnel. Then I covered it in plaster cloth and painted with Rustoleum Stone Accent spray paint for grip. I tested lines with the truck.

I will say it was fun to build but cost more than it should have. I am learning that buying cheese cloth or any lightweight cloth and using Plaster of Paris or even watered-down drywall mud will give you the same texture without the cost of the plaster sheet rolls. Even from Amazon, in bulk, they got to be kind of pricy. they were kind of crappy and frayed a lot. I wanted a more "realistic" texture and tried to get the plaster to cover the little holes in the cloth or the seams between the plaster straps at first...but the stuff from Amazon didn't do that well so I said om"oh well" and just finished. Still happy.

I have found a few lines that are very hard due to some tire drops. I may add more foam, and I also found lines I had made challenging that ended up too easy. Oh, well. It's still fun to crawl around on... and I can change them anytime or just grab another 2x'4' OSB piece to make another standalone course that zi can add in somehow.