This is a firecracker mortar that shoots a basic 6mm airsoft BB. I am not sure if this is allowed to be on this website but i made it when i was bored and found it cool so I wanted to share it with the world. I would suggest you use some strong filament like PETG.

you assemble it by attaching the Boom Boom Tube and the grip with the screw. then you put a firecracker in the cartridge and put that into the Boom Boom Tube. then you use some kind of wire “you can also use something like fishing line I just used some wire I found sitting around”. you take the wire and wrap it around the left over holes on the outside.

The Boom Boom Tube and the Grip may need supports I used tree supports.

Thank you for looking at my design.