Because yes.
I know it doesn't look exactly perfect, but I made it manymany years ago at school, I can't even remember which grade, and it works.
I would've taken a picture of it firing a rubber band, but all of the rubber bands stored as ammo on it broke as soon as I touched them (they were also very old)... Meh.
Features a fully rotating turret, detachable cannons in two sizes, three nails for storing ammo, wheels which rotate (but don't grip exactly well since they're wood), and a fine accuracy last time I tested it (you can aim like on a gun).
Maybe I should put some caterpillar tracks around the weels one day of some rubbery material if I somehow get some in a fitting size just to make it complete.