Sub Box Question

Has anyone ever used MDF (compressed cardboard) to make a speaker box? and does it work good?

I've built boxes out of particle board before that have turned out good as long as you cover them with fabric. But I wanted to paint this one, and MDF is easy to paint with out having to mess with fiberglass.

Also I know solid boxes should have at least 1 cubic foot per 12" speaker if they are installed the normal direction; but I want to install 4 12" speakers (2 upside down, and 2 the normal direction). Do I still need around 1cf for a speaker installed upside down, or can I save some trunk space and make a smaller box?

actually MDF is the norm at most stereo shops. works great easy to router and shape. i've only used 3/4 and 1/2 inch MDF in my 8 years of working at stereo shops.