It looks a bit of a dogs dinner inside but it seems to work fine. Unfortunately I stripped the contacts off the bottom of my Teensy board so I had to make room for the USB cable you can see in the picture below.

I tried a couple of different hubs before i found one that I was happy with and in the end I went for the Broadcom WiFi Adapter and 2 Port USB Hub as it included wi-fi and it works perfectly
The battery is fit inside the Tetris cartridge - I removed the back of the Tetris cartridge to free up a bit of space and I stuck an old plastic card out of my wallet on the back of it!
One thing I did do is snap the USB ports off the Pi Zero to ensure the HDMI connector sat flush with the side of the Game Boy Shell

The back view shows the two tactile switches used for the L & R buttons

A big thank you to wermy and everyone else involved in the project as i wouldn't have been able to make this without the guides and the forum
