I have been thinking for a while if it would not be possible to build something akin to bb0039 (but larger) from some "Brick, Round Corner 2 x 2 Macaroni" + some more.
Back when I was a kid in the 80:s I modified an idea from the Idea book LegoLet's Build and Play - with your Bricks where a rubber band powered contraption could set speed to cars.
I turned it into a "super cannon" capable to throw out duplo bricks. Now I got back to that idea, but wanted to refine it a bit.
I had an idea to put a spring inside the cannon to make it look nicer, and work more like bb0039, but the technic axle would not stay connected to the other bricks unfortunately, so I got back to using rubber bands.
The cannon may still misfire and throw out the internal mechanism if too much power is applied, but if handled carefully it works quite well.
Governor Broadside looks quite happy about the new cannon, but his soldiers seem a bit dissatisfied with having to carry the heavier ammunition...