I recently acquired MC measurement computing's MCC 134 hat for the raspberry pi. I use this hat to read three type K thermocouples in my coffee roaster. If you have used a raspberry pi 4, you know that the chipset on this computer can run very hot. I designed this fan shroud to work with the MCC 134 hat, using a 12 volt 40mm x 10mm cooling fan. Regular pi 4 fan shrouds attach to the pi in the same fashion as the MCC 134, and the hat blocks the use of most fans as a result. This fan shroud pulls the fan to one side and runs air across the chipset, through the gap created by the standoffs used to install the hat. In this fashion, coupled with a heat sink on the chipset a user can keep the pi 4 very cool.

Here is a link to the very good thermocouple hat made by Measurement Computing: https://www.mccdaq.com/DAQ-HAT/MCC-134.aspx