Does your bender have an angle guage on it? Mine was approximate at best, but it at least allowed me to duplicate a bend so both sides wound up the same.
I first drew it up in a 2D cad program. I drew my straight lines to represent the outside edge of the tube. I then had the program put the bend radius in. I could then dimension the straights, the length of the bend, and then get the overall length. It also showed me where the bends would start and stop.
I also read up on Pirate4x4. They have a great tutorial that describes a system of snapping chalk lines on the floor. I used both systems together and I never missed a bend. Well, I did have one that the overall width at the bottom was 1.5" too wide, but hey... Some judicious pulling and prodding kept me from having to waste it <img src="/forums/images/graemlins/kewl.gif" alt="" />. This was with a JD2 bender, and my first experience with it. I do know that the front hoop has many different bends per side. One of course that goes from across the top to down. One bend above the dash allowing the bar to hug the Apillar. Next, it bends just past the to of the dash back towards the front of the truck. One more bend back to the floor, and ALSO sort of back out to the outside. This one is a compound bend.
One idea that I'd seen AFTER I did mine was that some cages will run the middle hoop side to side, but then instead of a one piece front hoop, use two bars running from the middle hoop forward to the windshield and bending down to the floor. Then connect one straight bar across the top of the windshield tying in those two bars. This is how my rear half is done.