Ok last update for tonight, I cut off the armored fastpack from the lame backpack center piece that comes with the kit, I plan to attach them somehow to the backpack of the hase kit. Cutting off these parts left big holes on each of the fastpacks. I filled in the holes with the two part putty. I considered using styrene but the shapes were odd and it would have been difficult to trace the shapes with a pen. Anyways this was the easier way to go, I let the putty dry overnight, I sanded it down as much as possible and then filled in the remaining gaps with Tamiya putty.