i did something like that inside one of the wells up in the mountains, but not as complete as yours

https://steamcommunity.com/sharedfiles/filedetails/?id=2800220282

https://steamcommunity.com/sharedfiles/filedetails/?id=2800220341

https://steamcommunity.com/sharedfiles/filedetails/?id=2800220369

was pretty fun trying to cram stuff in there.. you can destroy the floor at the bottom of those and it opens up into an even deeper hole if you want an underground mountain lair like a Bond villain..