i think the question here is why do you want to make a cardboard gun?
Get a rectangular piece of cardboard & bend it into a circle .Paste the inside with hot glue (glue gun) and then put the string on it. When the paste it dry, cut the cardboard & there u have it. A HOLLOW BALL OF STRING!
you have to use a hot glue gun.
Yes if the power of the BB gun is >200 FPS (Feet Per Second) and if the pellets are >0.25g Source: I have a 450 FPS BB gun with 0.28g pellets and it will go through insulation foam with ease and scar you if you get shot by it...
how can i make a radio made of cardboard
how to make a simple model piano out of cardboard
I suggest the use of cardboard to make cardboard egg crates.
ehow.com/how_4744756_make-airplane-cardboard-box.html
You could not make it with entirely cardboard, but you could use it for wings if you wanted to.
Some cardboard and paper are recycled to make new cardboard, but the primary raw material for cardboard is wood (celulose).
You can make cardboard more durable by adding layers, using thicker cardboard, or applying a protective coating like varnish or sealant.
A bin can be made out of a cardboard box without doing anything at all to it. However, if the cardboard is in pieces, it can be glued together with wood glue to make a bin.
Cardboard boxes can be used for gardening. You can give your cardboard boxes away on BoxGiver