This is a light blocker designed to limit light leaks in a Game Boy Camera shell by blocking light from entering the rear of the ball.
Unfortunately, Nintendo designed the sensor circuit board with via holes directly behind the camera sensor, causing light to distort output images. To top it off, the original plastic shell has some translucence, which allowed for light to leak in - the yellow shell is particularly the worst for this.
With this light blocker, use any shell - even a custom transparent shell - and worry less about light distorting your photos.
This mod is non-destructive and no soldering is needed. Just open up your camera, unscrew the lens from the sensor board, detach cable, screw it in behind the sensor board.
There's 2 versions of this model: a standard, and one with looser tolerances. Standard is more accurate, but looser tolerances adjust for potential printing tolerance issues.
If you found this useful, please consider donating to my Ko-Fi account: https://ko-fi.com/gameboycamera
I've also had a few made from black PCB that I'm selling to help recoup some project costs available here: https://ko-fi.com/s/56613b6bae
The author marked this model as their own original creation.