@nxt-1 said in Idea: peltier hotend cooling?: A slight advantage can be had due to the higher temperature differential between the ambient air and the hot side of the PEC But the higher differential will only benefit you if the current heatsink temperature is somehow too high. And unless you add more fan cooling you won't be able achieve the increased differential in any case - so if the goal is to remove the fan then I'd be surprised if this was the way to go. Not knowing much about the geometry, maybe heatpipes would allow you to transport the heat to an area where there is more room for heatsinks and/or fans?