though I don't think you can reverse which side is hot/cold without physically flipping it over, and I believe the side with the numbers is the cold side
and you will need hotplate to spread the heat and act as a buffer, remember its not a good idea to get the lower amperage ones above 80c
I couldn't make a hotplate for a candle running at 3.3V/6A/19.8W because it wouldn't transfer the heat fast enough, I'd need a lower amperage/voltage
a thermos would have a different composition than a thick glass and wax candle though so Idk
Well to be honest after talking to my friends everybody would prefer a drone project so the mug one will be for another day while we biuld a drone. I was thinking though to have two of the unit on a thermos, one for cooling, one for heating. When the one would be cooling it could transfer some of its heat to the other one to generate power for more efficiancy. I might still have to play around with these, maby implement them somehow into the drone lol.
With a few transistors and a switch the current could be activated on either the cooling one or the heating one.