I change my layout often. Nothing is permanent. I purchased three pieces of pegboard and use those as a base. They offer a good flexibility in how large I can arrange my layout and are very inexpensive. My last layout was 4’x 10′ but this week we need a little extra room so I chopped two feet off the layout and used the extra piece of pegboard as a second layer on top of the 4′ x 8′ layout.
I picked up a piece of green felt at Hobby Lobby. That lays on top of the pegboard to give it a slightly more realistic look. It was hot when I recorded this and the ceiling fan was running. You will notice it blowing the felt on the upper deck. If this were a permanent layout, I would glue all that down, but next week, it will be used in a different layout.
I picked up some Lego knockoff base plates and used those for the long ramps. Those work great and were inexpensive. I also found a bag of 1/160 scale cars to add to the layout for more realism. I tried making a few Lego buildings to match. Those will get better.
The SCARM plans for the layout are here.