NOT MY IDEA JUST A REPOST FROM KIPKAY:)
Step 1: Things You Need
1. Medicine container or some thing like that (film canister)
2. Drill with 5/16 drill bit
3. Round ballpoint pen
4. Hot glue gun
5. 6 mm airsoft pellets
Step 2: Drill Holes
Using the 5/16 drill bit, drill a hole in the bottom of the container you are using. Using the same drill bit, drill a hole in the side of the container.
Step 3: The Barrel
Get a ballpoint pen and take all the " guts" out of it leaving just the round tube. This will be the barrel. Take the barrel and put it in the hole on the bottom of the container. After that hot glue around the the bottom of the barrel to make sure no air escapes.
Step 4: You're Done!
Take the lid off the container and put 6mm airsoft pellets. Put the lid back on and blow into the side hole and boom you have a mini airsoft machine gun