have you actually ever used MDF before? you do know that a 15"x15" sheet of aluminum is more than a 8'x6' piece of MDF
i used to work at different car audio shops building speaker boxes. i've used enough MDF to know what i can do with it. don't judge my ability to make something until you've seen previous work.
so once again, you guys need to quit telling me how to build my case. its MINE NOT YOURS.
and no, tin wouldn't be better than MDF. MDF actually absorbs sound and is easier to work with.