An insert that replaces the guts of an Atari 2600/7800 cartridge with a Raspberry Pi Zero (or Zero W). Perfect for Retropie. Installation of the Pi Zero requires no hardware - simply snaps into place. No permanent modification to the cartridge case is required and when installed the difference is only visible from the "business end" of the cart.
Access is provided for the micro SD card without removal of the Pi from the insert, but the insert must be removed from the cartridge in order to do so (unless you want to modify the cartridge, but that would make the mod more easily discernible).
Updated v8 includes provisions for a power button. As long as the listing persists you can find the buttons I used on eBay here. Buttons thread directly into the insert, no hardware required. I've also included an STL for a simple tool that I designed to facilitate screwing in the button... It's not required, but it does make it easier since the button is close to the inside wall and doesn't allow much room for gripping with the fingers. I'm using the instructions found here for wiring up the button with no additional hardware required.
I like to print this model with the face (port) side against the bed so it has a nice smooth / glossy finish with no layer lines. When printing in this way only a small amount of support is required for the posts to which the Pi mounts.
Installation into the cartridge
There are several videos on YouTube that will guide you through disassembly of an Atari 2600 cartridge. Basically there is a screw in the middle under the label and clips down both sides that can be undone by squeezing the sides of the top half of the clam shell.
The EASY way to do it is to remove or damage the label of the cartridge so you can get the screw out. You could then either deal with the damaged label or maybe print your own custom label for the cart.
If you're wanting to maintain the illusion of a fully original cart it's possible to leave the screw in place and get enough room to get the existing sliding insert, cartridge board and metal spring out if you're careful. This is all you need to remove in order to use this insert; the insert then gets carefully slid into the cart (it's a tight fit) and the case snapped back together. If you're not careful and pry a little too hard or just get unlucky the back of the case may crack a bit around the screw pillar. Generally you can carefully realign the cracked pieces during reassembly and if the cracks aren't too large they won't be visible - often even on close inspection.