RTV silicone is not the best choice for thermally conductive adhesive. We use them for high heat resistance but not for heat conduction. Get some thermal compound from an electronics store. It is not a glue but ensures maximum heat conductivity. then use any sort of mechanical fastener to hold the two parts together. look at your computer CPU cooling fins for ideas.Also used in lap tops
peltier cells are horribly ineffective. If you want a drink bowl heater look for one of those USB powered coffee cup heaters ‘puter nerds found so nifty.
Typically a USB port only delivers 85 milliwatts at 5 volts.
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