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 test still ran the Raspi into thermal throttling in less than 3 minutes.
But still, looks like convection may be a thing here, of course helped by the fact that the heat sink rips were now vertical.

Next I replaced both bottom and top by Malolo's versions that were basically nothing full hexagonal holes. That brought the idle temperature down to 55 °C and now the stress test took 9 minutes to drive the Rasp into throttling. Better, but still not there yet.

So I remixed Malolo's solid cas