hmm, one of my pi3's is in a nice alloy case that has a heat spreader pressed against the CPU chip.
now, my workload for it is very light weight, it runs a python script that sleeps for 2 minutes, then reads some weather data and updates a couple servers. so it runs very cool
ah, they have a pi4 version now...
https://flirc.tv/more/raspberry-pi-4-case