For my front bumper, I just got a large piece of cardboard(the side out of a refriderator box) and worked using the original bumper for dimensions, etc, drew out what I wanted the bumper to look like and started cutting and welding. You can see a bit of what the front looks like on page 6, issue 40 of the TDR.
I used 10" , 10 gauge flat stock which I had a shop bend to a channel with 1. 5" edges. Two pieces, one for each side of the winch, bent to angle back two places--hopefully to harmonize with the front of the truck. All the brackets, the center portion of the bumper, the winch mount and attachments is 3/8 steel, with 1" angle braces as appropriate.
For the rear I used 5" channel. The center portion is about 16 inches and is boxed so its a square tube. Then the two side pieces are welded to that with the open side of the box facing forward. The ends are tapered and boxed.
Its a fun project. This is the third truck I have built bumpers for.
Vaughn