Here's the WIP of the K-wagon That was Built For the Lead Adventures Forum
Build Something Contest, that due to issues of 3rd party photo sharing is now not a complete thread. This is a link to the original post on LAF

This is the actual beast that was prototyped in 1917/1918 I think
Below are the plans that I used to start making my own
Copies of my scale plans at A3
The following pictures are of the basic build.
Various Gauges of plasticard were used, tracks & road wheels some old 40k ones that I had (I know they aren't exactly correct, but this is a wargaming toy not a scale replica) The Mg's are from Northstar, cannons are turned down plastic rod.
Home made Decals.

Finished K-Wagon