How about a 2.5 cube box ported with MDF for a 12" havoc? Max height is 16-17", total depth 20-22 and width no more than 32. I'm sure you can build around those specs. I might need an amp rack and I want a visually appealing box with perhaps some lettering and something other than carpet to cover it. It's going in an 07 Denali. I made those measurements based on how much space I want to give up.