I, nor S.A.W. Armament, or anyone else is responsible for any injuries that accur from making this device or any devices based off its design. The responsibility is soley placed on the individuals or groups that decide to create it. Ignorance toward clear and present dangers, as well as technicalities and variables from indevidual components or utilities due to inexperience, WILL result in eventual injury to one's person, property, or surroundings (including other people). You have been thoroughly warned and advised, please take care in what you do to ensure your own safety as well as others.
Gather the supplies: 6mm barrel or pen tube, hot glue gun, and a normal sized pill bottle with an easy to open cap but is still tightly sealed, and 6mm airsoft bbs (preferably lighter wieght bbs from walmart, as the quality is not a factor and light wieght maximizes effectiveness) (These are just the supplies needed for the initual test to give you an idea of the concept, more supplies will be needed for taking this concept further)
1. Cut a hole just large enough to "squeeze" the barrel in in the center of the bottle cap and glue the perimeter of the hole around the barrel with hot glue for a nice seal. (The barrel should have about in inch or more inside the bottle.)
2. After that, cut a "slightly" larger hole on the side of the bottle toward the bottom.
3. Fill the bottle up to the end of the barrel within the bottle and screw the lid back on.
After you have finshed, take it outside and test it out. You blow hard into the hole you created on the side of the bottle. If done correctly, it will have some great distance just from your breath, so set up a target or get some open range of about 100ft. just to make sure.
If you blew hard you would be amazed by the results. Now imagine using pressurized gas and a metal cylinder in place of the pill bottle, and a longer barrel for more range. Then find the body of an airsoft gun that is a replica of one of your favorite guns thats internals are busted or can be used on another, and find a way to insert youur newly made gadget. thsi concept can be applied to most airsoft guns so let your imagination run free. One word of advice though, make sure to have a way to regulate the air pressure of what you are using to blow into the device so as to not bust any of the sensetive pieces or cause injury, and to stay within velocity limits of the field you play on.
You can see how I fitted the bottle in on the S.A.W. Armament model below by using the refrence pictures. I glued the outer barrel to the cap so I could twist it off and back on between reloads.
(P.S. If you are woundering what that is on the side of the AR15-styled airsoft gun I made, it is an incomplete prototype for a night vision viewing screen which works well.)