12" sub box

Hey everyone, havent been on here in awhile because ive been busy with school, but with winter break coming up Id like to do a little project and was looking for a little insight if someone can help. So I have a 12" sub in my truck (2009 double cab) that is sitting in a box on one of the seats. I want to build a box to fit behind one of the back seats. Ive found a few threads with similar info but nothing thats helped too much. Now I want to say before anyone asks, I really am not big on specifics so cant really give info on what my set up is, honestly didnt pay for nicest sub and amp set (college budget). Not sure if this is important but I have my amp installed under my passenger seat. Ive seen most threads say 8" and 10" are most common behind seats, so im not even sure fitting a 12" behind the seats is possible. Any info would be helpful, and if anyone has a design blueprint for a box that would be awesome! Thanks everyone

 

********* makes an enclosure for a single 12" subwoofer I believe.

 

I've got a custom sub box and amp rack from mr marv that I'm selling, will fit great in your truck

 

Just ordered my dual 10 box from mr marv. Great guy to do buisness with!