Bruski: a couple subjects to cover. One at a time. Underground shooting range:
Have you considered digging a large pit to about chest level and laying one or more
lengths of 2\' to 3\' diameter pipe, plastic, cardboard, or whatever.
Leave a walkway on both ends of the pipe(s), bury the pipe(s) and put a roof over the walkways
(for subterranean).
Install lighting, place targets in one walkway and the shooter on the other end.
I have been racking my brain for years trying to think of ways to build underground for cheap, not
have the sand cave in, and my neighbors not seeing me doing it.
Hope that makes sense. -Stirlingking