Well this is my first instructable so please don't say anything bad about it. Note: If someone this in a classroom, please comment about it.
Okay so this just a simple BB Blowtube using one pen. Another pen will be need in order for a bb holder. The holder is optional but recomended. So lets get this instructable started.

Step 1: Step 1: the Blow Tube

Well all you really need is one bic pen (or at least one that can fit a 6mm BB. I used second chance BBs for this.(Gotta go green right?) So anyway you just need to remove the ink/tip part of the pen and the part on the end of the pen. This pen can only shoot one BB at a time, so only load it with one BB. Blow into the Narrow end to shoot with it. Replace the ink/tip to disguise it as a normal pen.

Step 2: Filling the BB Holder

Okay so this will require a thin clicking pen. Take the pen apart and fill the inside with BBs but leave a some room for them next step.

Step 3: Finish It Off

Put the spring of the pen in the shaft so the BBs are less likely to fall out. Replace the rest of the pen except for the ink part. There you have it. The finished holder. Bring it to class and have some fun.