Just read about your business you are starting. If you are good with aluminum and can duplicate the door panels (and rear panels), with a roll on the top so they fit correctly you would sell all you could make. I don't know anyone that produces these. Most just sell a sheet of aluminum and basically you build it. I am sure the 61-64 panels are pretty close in size with exception of mounting holes and maybe handle openings. You have some good ideas....good luck.
I like your hammer rack, but I think that smaller holes should be used. I would like to see something like a square piece that you could put onto 4 legs to hold a lot of hammers. Right now, I throw all my hammers into a cardboard box, since I don't have room for them in the tool box. Probably should thin the heard, but you never know when you are going to need the one you just gave away.