Behold, a home-made Pokéball (that you can build yourself) that wiggles when a rare Pokémon is nearby. It’s connected to a cellular network — powered by a Particle Electron—and has a GPS chip inside. It asks the Pokémon API what Pokémon are nearby, and if there are any rare Pokémon, it wiggles to let you know to pull out your phone and start hunting.
Here's instructions and code for building your own: