'I used IFTTT (If This Then That) to define radii that would send messages to the Photon if my phone entered or exited them. (I would later walk the other 5 members of my family through the same process.)'
'Et voilà! The glass in the hinged metal rim broke in transit, but I kept the metal there anyhow. The glowing B is black paint on acrylic, lit by the tail end of the LED strand hanging down, and it flashes a different color for each member of the family'