Battlefoam foam is specifically made to be an awkward size so you have no real choice but to buy their expensive bags if you've already wasted money on their expensive foam.
You could either cut your losses early and just get normal-sized foam, or you can continue throwing you money away at Battlefoam.
Battlefoam trays come in an inexplicably wild variety of sizes depending on who-know-what-logic, but their common generic sizes are 15.5"x12"
Pelican has a calculator:
http://www.pelican.com/calculator/
I have a friend that claims the 0550 Pelican Case holds Battlefoams. But you'll be needing a 4x4 grid of buyer's remorse to fill up that thing. It's ridiculousl expensive, but I guess that's the price you pay when you deal with battlefoams.
http://www.pelican.com/cases_detail.php?Case=0550