Quite a few years ago now, when Dogs of War were still a thing, I was going to write a bunch of articles about how you can kitbash any unit with the existing plastics range.
Most were simple.
For example, here is a smaller calibre cannon, by cutting off some of the length of the normal cannon, wheel swap, and using the mortar struts:
A Paymaster (or Empire Merchant) using the fat Bret body and some bits.
Ruglud's armoured orcs - just with the 6th ed archer bodies, arm swaps and a 7th ed Empire crossbow (they are bigger scale).
Slayer Pirates - just hand swaps with pistols. Could easily be painted with red beards
Ghazak Khan, mainly with a wicker shield cut up to use as armour pieces.
Dark Emmissary from a corpse cart rider, and various other bits.
There were a bunch of other things I made, but I don't think I have photos of them handy.
The Galloper Gun kitbash I really liked - may take a photo of it someday.