Raspberry Pi 4 Chimney Fan Case

This case is designed to maximize airflow around a Raspberry Pi 4. It pulls cold air in from the bottom, blows it up a narrowing tube to increase speed, and across the hot parts of a Raspberry Pi, sending the heat out the top. It allows access to all of the USB & Networking ports, the monitor, sound, and power ports. The expansion GPIO pins are blocked, except for really thin cables (like fan power cables), and the SD card isn't very accessible.

It requires (or, at least, is meant to work with) 2 extra things:
1. A 90mm computer case fan
2. A Raspberry Pi heatsink case... one of the flush ones that are all metal and fins. It may fit without, but I haven't tried.

Other Notes:
If you use a 12v fan and attach it to the 5v power line on the raspberry pi, it should produce plenty of air without much noise.
There is a spacer which is about the size and shape of a fan. It's supposed to go above the fan, with the support bars AWAY from the fan. This spacer exists to help reduce