When it was released in the late 80s, Game Boys were pretty revolutionary for their small size. However, you couldn't really attach one to your keys, could you? Fortunately technology has come on a bit in the last three decades, prompting tech tinkerer Sprite_TM to have a go at creating a Game Boy that could. From Scratch.
This is the full build video, but skip to 37 minutes to see the tiny console in action:
Using a 3D Printed body and assembled parts from all over, including a tiny screen, Sprite_TM was able to make a fully functioning Game Boy Color. Obviously, the original cartridges won't fit in it, so instead it is running on a Game Boy emulator. Check out the full video if you're interested to see how he did it.