Now, we get to open up the cartridge and turn it into a proper console/controller case!
I picked up a couple of old games at a retro gaming store for just a few dollars each. (Note escalator for proof of shopping mall visit.)
Use your Gamebit security screw driver, and unscrew the three screws.
Now, open up the case and remove the old game ROM PCB.
Place the bottom shell (the one without the game label) on your workbench and then set the Pi in the case behind the lip, as seen here. Trace the Pi with a marker, just so you have a reference point later.
Now, mark some spots to cut out the lip so the ports will be accessible.
Use the box cutter to score the plastic along the base on both sides, and then cut straight down to remove the two pieces of plastic that would be covering the ports.
Using three strips of double stick tape (for the desired height) affix the Pi Zero to the bottom shell.
Using the same method as before, cut a matching set of port holes from the top shell's lip.
In order for the Joy Bonnet to sit on top of the cartridge, yet connect to the Pi Zero, we'll need to cut out a small port from the top shell.
You can either measure accurately the position of the header pins and transfer that to the top, or close the shell and squeeze gently to transfer marks from the pins into the soft inner plastic. Use this as your guide for marking and cutting!
Use a straight edge to mark cutting guides a little bit larger than the pin marks, then score these lines with the box cutter until you break through to the other side.
Once you've cut all the way through, pop out the piece, and then clean up the edges a bit with the knife or a file. The nice thing is that this window will be hidden so it doesn't need a perfect finish!
Now, you can close up the shell, and fit the Joy Bonnet into place.
Go ahead and screw the three screws back into place, and it's time to play!