Would be cool if Laird or one of the other thermoelectric ceramic (TEC) manufacturers made radial, cylindrical TECs. So far I’ve only seen them be flat and square, or they cut the flat square out like this

instead of in the radial direction. There are some made for research but not commercially available as far as I’ve been able to find.

Also TECs are very brittle too so vibration if that tail pipe would have to be dealt with for them not to crack. I’ve cracked a few myself but i use for heating/cooling in machine design for work.