I sketched out two more designs that were modifications of my first working model. But then I got side tracked with more back surgery and both new designs (#2 and #3) were partially assembled for over a year.
This week I took two days off work and made a commitment to get them up and running. At 1:00 PM today my second design (with a rotating flywheel of sorts) started running, and it has been going strong for most of the last 8 hours. It has not run from the heat of the hand yet, but it has run on sunshine with no ice, and when inside it runs with ice when sitting next to a 60 watt light bulb. I have a high level of confidence that this engine will run from the heat of the hand after some minor adjustment to the crank shaft and the addition of a little helium.
I believe the last of the three designs will be the most efficient. It uses the same ultra-low friction design of the first engine with the addition of a rotating flywheel. It should be also up and running by the end of the weekend. After that I then have to get back to the text and finish up all the assembly instructions and organize all the pictures and illustrations. The end of this project is in sight.
I don't know if I still have a publication deal or not. I would not be surprised to learn that the offer has expired. If I have to start over finding a publisher I will be looking into self publication with print on demand.