Pleeeeeeeeeeeeeeeeease help me EQD sent me here (to any papercraft ponies lol) and I have decided to start making papercraft ponies. but, unfortunately I can't see any pictures that EQD has sent me from deviantart...Halp
Alright, basically, anything that's a fan shape is a truncated cone; in other words, you take the straight sides, and roll the piece together so they fit together. The carriage frame is meant to be folded together like a box, only there's a giant half-hole in the middle. The bore is a simple cylinder that you roll up and stick inside the barrel. If you're printing on letter paper, you should be rolling everything along the grain.
I do like that you used the correct terms for the parts of this fine artillery, but just to clarify, "gun" typically refers to ship-based artillery while "cannon" typically refers to land-based artillery. Although the barrel could be the same with the only difference being the carriage.