Regarding the Brodak handle, where is all the weight, i.e., in the plastic bits or metal bits? If plastic, I would suggest using "structural foam".
I once worked at a place that made molds for various products that were made from structural foam...one being waterskiis (Kidder and O'Brian). Another product was an in-ground...in ROAD...utilities box (wiring or whatever). The "manhole cover" was about 30" diameter, and foam. Maybe weighed a pound or two. You could drive an 18-wheeler over it, beat the puddin' out of it with an 8 lb sledge...no problems. Amazing stuff. Dunno if it'd be "fuel proof", but tend to think it'd do fine.
We did have some problems with the usual "ball check" filler valves for this mold, because of the size of the main case mold. The boss was "away", and the customer said the teflon check balls just came squeezing out of the filler neck. I looked at the problem and made a "blade valve" from some scraps of UHMW plate and a block of aluminum. I had no idea if it would work, but them was desperate times. It did work, and the customer was wildly happy....

Steve