Here is a fully functioning chip-carved 1:12 scale antique fireplace bellows.
It is carved from pear wood, real leather gusset, and turned brass nozzle. I made sure to carefully drill the hole all the way through my brass rod before turning the nozzle with the intention of making it work... but I didn't really believe it would...Imagine my delight when I put it up to my lips, pumped it, and felt little puffs of air!!!!!! That means it is perfectly sealed and the valve in the back is functioning :)
The air intake
On the inside of this hole is a valve that when the bellows are opened it takes in air, and when pumped, the valve closes, forcing the air out the nozzle, thus fanning the fire!