We have a hand-wound impeller fan bellows for the log fire in the dining room and it makes a devil of a racket when you turn the handle. My wife hates it so I made a much quieter version that runs off a couple of AA batteries. Basically it is http://www.thingiverse.com/thing:7350 with a handle and battery holder stuck on, but I've improved the parametrics a bit.If I run it off 12V it beats my 110mm forge blower!Print case, impeller and lid. Attach motor to lid with 2 x M3 screws or similar. Warm motor shaft and insert into hole in base of impeller. Do not trim printing goo strands off the interior of the impeller as it makes a handy filter.Ensure that:a) Impeller clears motor mounting screws, and b) Impeller is fitted centrally on the motor shaft. c) Impeller will rotate in the right direction to "brush" air out of the outlet.Fix the lid to the case with 3 x small countersunk woodscrews. Melt a wad of aluminium foil or slice of beer can to the distal end wall of the battery compartment to electrically join the ends of the 2 AA batteries.Fill the notches at the proximal end of the battery compartment with wire, solder etc. to press on the terminals of the batteries. Wire that to the fan via a switch. The switch just glues into place on the little platform by the grip - I'm using one off an old keyboard from my Amstrad days.Do not look down it just in case something solid comes out!A nozzle may be made of any convenient tube or sheet metal and fixed to the outlet with duct tape, but it's usually not worth the bother. I'm thinking one of those skinny alcopop cans.