Looking for optimum Box design for 15" Peavey Black Widow

I have an extra Peavey Black widow lying around and would love to put it to its full potential. I am new to building custom boxes but plan to make a couple in the near future. I'd like to start with this one.

The optimum design will depend on what you want to optimise this box for : smiley1
What other speakers have you got, and what do you want to use the finished system for :