I am looking to build a rear bumper similar to Marlin's design for my '94 P/U.

Everything seems simple enough, with one exception. Does anyone know what radius the bends are for the tubing that goes around the rear corner of the truck? Also, does anyone know of a brake rotor that has a similar size hat to use as a "die" to bend the tube around? Yeah, I know, I should be using a tubing bender, but I don't have one, and all I need are two 90 degree bends.

Pictures of the design I am discussing can be found on marlin's site at: http://www.marlincrawler.com/armor.html