After checking prices, I decided to make my own box. Started with a 3/4" sheet of marine grade plywood and started cutting. I think the top piece is roughly 57"x33" with some slots cut for the roll bar, and the vertical brace is somewhere around 22" tall. I'd have to measure again to be sure. Made a door panel for access without opening the gate, hinged and carpeted. Looks ok, but I think I can do better with my next attempt.