I was at my grandfathers the other day and saw in his junk pile ( he collects and takes stuff to the shredders 4 extra cash ) he has a 500 gal ( I think ) fuel oil tank with 1 rusted out side ( the kind that look sort of egg shaped from the side, but have flat sides )... seems if that were cut in 1/2 lenthways, the top curve could be used for the 2 sides of the rear bucket, and the bottom could be cut in 3 sections and used for the cowl.. a little extra 16 ga sheet metal for the door section, and firewall and floor... pay my grandfather like $50 to cover it's weight in scrap and I could probably build it for under $100