Convection Cooling Raspberry Pi 4 Case

Originally I used the [beautiful case](https://www.thingiverse.com/thing:3723561) made by [Malolo](https://www.thingiverse.com/Malolo), to be precise the solid bottom and top cover with the hexagonal hole pattern in the center.

Unfortunately, just sitting flat on the table the Rasp ran about 65 °C idle temperature, despite heat sinks on all hot chips.
At some point I randomly put the case on it's long side and immediately noted the idle temperature to drop to 60 °C. But doing a 4 core stress