There is a chap in the US offering lazy Susan rotating racks in different sizes. Prices are reasonable, but shipping would be a bear.
Made from 3/4" plywood. Square base, ball bearing lazy Susan plate, circular base for the butts with notches, pipe column, pipe flanges top and bottom, smaller upper disc with notches for the barrels. A lot of guns racked in minimal floor space. Sizes for a dozen guns up.
Google "rotary gun rack plans".
