well, at that time Huon Pine was very plentiful .... now it's very rare & just as expensive as a real torpedo. Huon Pine is heavy & sinks in water, but doesn't rot so at present there's an industry for divers recovering logs that were lost in shipping on the rivers :)
a couple more I "found" in my photobucket album ...
armed & armoured excavator, used to dig out underground forts, Second Battle of the Maginot Line, 1964. Armour is internal, protecting vital parts only.
SdKfz.225 -- to give better cross-country ability in the soft sand of Nth Africa, Rommel suggested that the SdKfz-250 be given an extended chassis.