I converted my old Habagat bag into a something similar to a TAMRAC. I'll post the pics of it soon.
Basically, what I did for those cushioned divisions we see in TAMRAC bags was I cut rectangular pieces of illustration boards, sandwich em between 2 insulating foams, covered em in black fabric, sewed em up (actually my wife did the sewing) then, presto, i now have cushioned divisions. I also did the same for the side cushions. Then I also placed a large piece of illus-board-insulating-foam piece for the back cushion. For the front, I just covered a piece of insulating foam with black fabric. Now I have a TAMBagat camera bag...