I'm looking at starting some outdoor forging, in an area with no electricity with a few of my friends. What are the best designs for bellows, weighing effectiveness and ease of creating/price? I've looked at pot bellows and bag bellows, and preferably they would require little more work than those. I've checked out box bellows, but because we don't have access to uniform sheets of wood, those would be hard to accomplish. Thanks for your help.