Here is one I put together for winter indoor shooting in the wet Pacific NW... A green house left over from my wife's commercial greenhous business. [ she retired 4 years ago ]
It's a frame I built and welded together from donated pipe and commercial greenhouse plastic... Not much at all involved, and very low maintance.... But it is dry and out of the elements for those long wet winter days and nights. I plan on covering it with metal soon and in addition to a range, I'll be using part of it as "dry storage" for kubota tractor and ski boat on the right hand side.
This one is 20x50' and has lighting, propane heat, and forced air ventilation.. During the summer it's way too hot to shoot in here so I move these targets, and several others out into the woods surroundung our log home/cabin, for more of a realistic setting.
In the mein time it allows for day or night time shooting...