How did you make your sub boxes?

I'm getting ready to build a pair of sub boxes for my trunk, one for each side that will fit triangularly into the corners of the rear seat...what should I use to make the box besides the boards? should I glue the sides together or nail them?

my biggest question is, how should I secure the boxes in place so they wont slide around in the trunk, I dont want to use Velcro thats just lazy I want to do it right, how can I keep them in place?