I finally got some time over the holiday break to sit down and finish the project. Everything if functioning as a system, though the bluetooth is still wobbly and the Bluetooth controller needs some help after boot to connect up to the system, but everything else works pretty flawlessly! Here is what happened in order to finish up the project.

3D Printed Spacers and Guides

I designed a spacer to mount the cartridge connector to the side of the ammo can. There are a couple holes in the side that used as the mounting point. 

I also designed a guide plate to put on the top of the of the gash I had to cut into the top of the ammo can. The slot helps guide the cart to the connector as you push it in. I did have to widen the hole on the top quite a bit to get it to fit, but the end result works with the design. 

Exposing USB

The small USB hub showed up and I was able to finish placing and gluing down all the USB components in place and soldering the USB breakout wires to the cart pads. I also soldered a USB type B breakout board to the cart connector.  I then connected the the whole system and it totally worked! After bolting the whole cartridge and connector assembly together the system stopped working. I think there is a spacing issue and the cart needs to be pushed in further. After bolting all the parts to the chassis the issue went away so I'll probably just watch for this and see if I can improve reliability later. 

This is at a point where I can pull it out with family and friends, set it up and play some of the games. From here I'd like to figure out how to improve the reliability of the bluetooth connection. I'd also like to play around with some of the Retropie display themes and find something that is a bit more "Ready Player One" themed. 

USB - I also really hate opening up the case every time I need to connect a keyboard, so I might expose a USB port on one of the faces so I can access the USB lines easier.

Pi 4 - From the stuff I've seen about the Rasberry Pi 4 I think it would be sweet to try and upgrade the SBC. 

This is the first project I've finished in a long time. Its at a level of completion that I'm pretty happy with which really is amazing. I'd really like to redo this project and try to make a way that it can either play a given game right from the cart or switch to a "flash drive mode" and just pull data from it that way. I'll have to see if there community projects that have already done something like this and build off them.