I also purchased a set of propellers of Amazon.com and attached one to a DC motor.   We were having trouble finding a fan that would work.  It's still not the most powerful fan but it does produce a breeze.

I also grabbed a empty deodorant can and screwed a arm to a servo motor to the bottom of it.  What I'd like to do the next time our group meets is see if Chris's continuous servo would work on the bottom.  What we want to do is have bubble solution inside and have the servo on the bottom crank it up.