Although much smaller of course and everything is a lot less heavy, Amphicar body is technically much more difficult to repair than a flat sided DUKW ! The panels are almost all double curve and were cold formed making them prone to springing so should really use a colder weld like TIG not MIG. Also Amphicar originally used a strange rolling crimp welder to seal the bottom of the panels, You can see it on the rear quarters on original cars. Never seen anyone able to reproduce that. For those that have seen Wheeler Dealers their method of folding the metal over is totally wrong, the best method is spot or plug weld then run a very thin bead of weld along the edge to permanently seal and grind back. Of course all body repairs below water line should be lead, as they say anything but lead is just temporary !