did you contact them ? Is hard to build a good quality Sterling.
prob gonna be a couple thousand. most home built ones are in the 3-7% range.
Brillouin is building a LENR device to make hot water. He has figured out the action that all the scientists were using for hydrogen catalyzation on nickle and platinum, and sped up the process to milleseconds, creating a "free" energy source.
Lower down post , you can find a link to build your own.
second link goes to PESN, where you read how it works.
https://permies.com/t/14256/alternative-energy/Rossi-Cat-real-just-not