another nice thing would be a molded muliple rifle rack, something like below with bottom and upper sold in 6 rifle packs... as you add more guns you add anothe package, tops and bottoms seperate with the bottom deep/depth enough to hole a large rifle with BIG scope on it... also another advantage would be staggered heights so you can rack your shorter guns like ar15's and have another rack for your longer gun. even offering 4 gun, 6 gun and 8 gun long modules. you could mix and match... have an 8 gun bottom, with 2 seperate 4 gun uppers at different heights.
also make them so that they have pegs for rubber bands or bungy to securly hold the firearms in.