You might do better to make a portative organ, Jack! They have a bellows with a chunk of granite on it. You lift up the bellows and let go and the weight causes the bellows to fall the air being directed through the pipes by a keyboard. The resistance in the system ensures the bellows falls at a reasonable rate. Periodically you lift the bellows up again. It means that the bellows hand is not fully occupied with the bellows and so can play the keyboard, unlike the Indian Harmonium. To buy one is serious money as you can see here.

Mind you 8ft pitch organ pipes would not exactly make a portative organ :-)