My first book accomplished this by making some radical changes to the engine design, basically turning it on its side to reduce friction. This proved very effective and created an engine that will run from the heat of my hand. I believe I have now solved several of the engineering puzzles required to make a traditional looking Stirling Engine that does not have to be turned sideways in order to run from the heat of a warm hand. Both of the engines I have tested to date have successfully run from hand heat with the addition of an ice cube to the engine top. I am confident that under the correct conditions these engines can be made to operate on hand heat without the addition of any ice.
This is great news for those of us who have always wanted a heat-of-the-hand Stilring Engine, but wanted to build it on a budget. The keys to this new design are the bearings. I have found some material to make bushings that is easy to work with, very affordable, and available for ordering online. I have also found an easy way to make clear sidewalls for round engines that uses bent acrylic which can be custom fit to any dimension needed.
Here is a video of one of the recent test runs for this latest engine: