I am looking to build a prototype for an idea that I have and not sure where to begin. I am looking for electronic parts (SMT?, microchip?...not exactly sure on terminology) that can communicate with each other via a transmitter/receiver relationship and give off vibrations at a given distance (like an alarm). They would need to be small...maybe the size of a coin or smaller. Can anyone help me figure out where to get something like this? Thank you, Dustin.