Robert Sleath
built this steam-tank for his Victorian Science Fiction games.
"I assumed that out-of-the-way colonies would not be priority destinations for state-of-the-art weapons. Therefore commanders or engineers on these posts would have to come up with something on their own. This is one possibility. "
The Dortmund Wargamers site has more photos of Robert's work.

The engine and wheels are from an old Citadel dwarf landship. The armour is card with dots of wood  glue for rivets. Sandbags are green putty.

See another view of the improvised tank in action