Orange Pi Zero ABS case you 3D-print is a very nice one... But it is not suitable for active cooling. The openings are also not enough for passive cooling. And with the v1.4 PCB it is impossible to put in a case.
An older v1 board with only "aplay" executing starts at 46 C and ends at 65+ (thus throtteling) in 10 minutes - inside the case.
I would like to see a newly designed one for your next manufacture batch...