This original was a block of hard foam, found floating down Ashton Canal where we use to sail, when rescuing an errant boat. it already had a basic boat shape, mainly landing craft/barge shape, found I could carve and shape like a piece of wood, so soon hollowed out, but with nominal 1 1/2" thick wall, virtual unsinkable, hence the name :-P. Once I had raided the spares box, for running gear (I was temporarily on the dole) and quite literally rammed it through foam hull and with a splash of paint came up with this "Vietnam River landing craft" ish!! (Motor: 540 type) (6/10)