This is my most useful Stirling engine so far. Running on a 3-wick candle it will run for hours and charge a cell phone or run small electronic devices. On an alcohol flame it runs much faster and will run larger loads as shown in the video. It seems to be quite durable as well. The main change I've made is to make the displace/regenerator from a spiral sandwich of aluminum mesh and steel wool. This seems to keep the steel wool from compacting and shifting around, a problem I had been experiencing.