So I see on some projects a series of things called Targetron. What is Targetron?
It's a machine that allows you to create a "target", which is a bunch of walls made from different materials to test things on. The bonus is that the walls can regenerate themselves on demand: you press a button and they are back in shape.
Searching for "targetron" in-game gives you Sandwichlizard's save in the first slot btw.