http://www.carshopinc.com/product_info.php?products_id=5550
If you don't care exactly how shnazzy it looks, you could buy something like that or make it yourself. I used one of those on my firewall, cut the tabs off for the frame and sectioned about 2" out of the center so that it was snug on my battery. Although that's prolly because I think I ordered a large one instead of a small one, dumbass.