Designed around a Raspberry Pi 3 B+, I wanted to run multiple operating systems without having to run BerryBoot, or in general having to partition a microSD card. Having card storage on the side of the system allows for quick swapping of the OS without having to search for another card.
This design has the fan turned as to blow air out of the casing, along with a huge amount of ventilation on the top and bottom of the system. Even with the wide vents on the corners of the case, very little amount of dust should accumulate so long as the fan is on. The fan has a minimalist guard built into the case to protect it from stray fingers and kitty paws (My cat hops in front of my TV and walks on the system)
Raspberry Pi 3 B+
2A Micro USB Power Supply
Micro SD Card (8GB to 64GB)
30mm x 30mm x 8mm 5V Fan
M2 x 10mm Screws
Windows 10 IoT (Must use Sandisk Class 10 32GB MicroSD, and use Raspberry Pi 3; not 3 B+): https://www.microsoft.com/en-us/software-download/windows10IoTCore#!
Retropie (Built on Raspbian Stretch Lite): https://retropie.org.uk/download/