I have thought about an outdoor shooting shed that could be mostly closed up with only a small shooting port, and a small heater inside for winter use. I would have removable side panels with bug screening when the panels are removed for spring and summer shooting. Room enough for at least two shooters. A roof overhang to protect the gun barrel from rain or snow. I would do whatever possible to keep the weather out even in a driving wind. There would be a wide bench for accessories (bullets spotting scope, and whatever else might be there. Enough room to lean gun cases and other paraphernalia against the back wall. If the shed does not wind up too heavy, I might consider some bicycle tires to make it mobile and some ATV hitches front and back so I could pull it around to vary the shooting distances.
I'll bet I'm not thinking of everything. The reason I posted this is because I am planning a construction of a such a "shooting shed" next summer and I'm looking for ideas. I don't want it to be finished and then have to say, "Gee, I wish I had done this or that. It is a one-shot deal.