The heat sinking that works the best for me.
SolarForce L2P 1x18650 cell powered.
Got a used alumin pan washed it out ( first wife's birthday cake came in the pan).
Cut out what I needed and doubled it over and lubed (plumbers Grease) put back together and it gets warm fast.
Now that was Not my Idea!
so a Big Thanks to the one who posted about the Pan because it is thicker than foil.