I wanted something to mount raspberry pi with inside the original NES console case. I found some models, but not a complete kit that fits my needs. I've taken two sources (look at remix sources section) and modified a few of them. I also created the mount for holding raspberry pi, and created the HDMI/USB port myself but using one model to fill in the side holes of NES. Feel free to modify them if you need to move holes around or whatever. The front USB ports I modified to be bigger as I didn't want to solder USB ports. I instead glued USB extenders inside the front ports for simplicity.

This is a complete conversion kit (if you want to replace the lid of NES, I also have another object for that - https://www.thingiverse.com/thing:6248599). The caveat is that it require you to dremel the rear port area out to be replaced with this kit.

You will need to dremel out the back port area to replace it with this kit's USB/HDMI port. I'd suggest printing this first then measuring out the area to cut, then use epoxy putty to fill in the gaps. Since I painted my NES, it wasn't a problem.

Those are the parts that I bought to build the case with:

Raspberry Pi 4
PowerBlock - For hooking up the power button to raspberry pi (https://www.petrockblock.com/powerblock-raspberry-pi-power-button/)
USB Power cable - https://www.amazon.com/gp/product/B086W5TSZB/?th=1
USB Extension cables - https://www.amazon.com/gp/product/B08FTCKH5H/?th=1
USB Power plug - https://www.amazon.com/gp/product/B0811H9GQ3/
HDMI internal cable to connect to HDMI port - https://www.amazon.com/gp/product/B088B3VZFH/
HDMI Port - https://www.amazon.com/gp/product/B08GRZ321W/
SD Card Extension (comes with sticky pad to attach it as shown in my picture) - https://www.amazon.com/gp/product/B07WWVBK8V/