Raspberry Pi 4 Case

### A simple case for the Raspberry Pi 4.

I wanted a case that I could easily modify to accommodate a hat or small LCD display.

**Features**
* Well ventilated to handle the high temperatures that the RPi 4 can generate
* Compact - I wanted the footprint to be as small as possible
* All external ports easily accessible - generous cutouts so that connectors can easily fit.

**Possible future enhancements**
* Cutouts for GPIO & Camera connectors

**Notes**
* Requires the following hardware (4 of each):
1. M2.5 * 6mm countersunk screws
2. M2.5 * 10mm countersunk screws
3. M2.5 * 20mm standoffs
* The upper and lower case parts were designed to fit tightly together. The parts I printed will snap together and hold without any screws. You may need some patience to get it to fit.
* Slicer settings used: 0.2mm, 0 top and bottom layers, 20% infill with honeycomb fill
* New version of Upper Case has a cutout for LED indicators.
* Update to V37 with smaller cutouts for USB,