Marshmallow Gun
This is my the marshmallow gun, it works similarly to a blowgun, and is a lot of fun, especially with kids. My niece and nephew love them. There are plans to make your own.
Marshmallow gun
It is really simple and cheap to make. It is made of 1/2" PVC, either pressure rated, or cellular core. Materials include about 1 1/2' of pipe, 2 end caps, 2 tees, and 2 elbows. Just glue them together like it shows in the picture. The marshmallow is just inserted into the mouthpiece, and then you blow into the mouthpiece.