Cannon would need to look authentic so American Civil War vintage would be the best.
What you need to realise is that the mechanism and wiring take up the bulk of the space.
An idea would be to paint some MDF model cannon/wagon wheels found on ebay. I noticed they sell for $2 each and would look neat in AC/DC colours. The trick would be to make an authentic cover which looks like a real cannon.
Also need to be aware that space clearance is critical especially on the right side because of wiring and ramps.
