Ever notice how unevenly some foods can cook in a microwave oven? San Francisco area maker Zeke Kossover came up with this clever method for visualizing the microwaves inside a microwave oven by embedding a matrix of tiny neon lamps inside a sheet of acrylic.

Microwaves are invisible, so you can’t see them inside microwave oven, but their presence can be detected with neon lamps. The changing electromagnetic field from the microwaves will make charged particles move, and so the electrons in the metal legs will move creating current. This current makes the lamps glow.