Looking to use up some more of his flexible LED strip, Hackaday alum and Tindie writer [Jeremy Cook] tried for a funky accent to his dinner or coffee table: light up coasters.
Using his CNC router to carve out two pieces of translucent plastic to house four 3V CR2032 batteries, four pieces of LED strip, and some wire, [Cook] had created a pressure plate circuit that activated once a drink is set on it. The original layout of the circuit, however, didn’t work, and the space for the LED strips proved to be too small. A quick redesign and some more time with his router resulted in an almost working product. Initially intending to use screws to secure the coaster, hot glue provided the perfect amount of spring once he had thinned out the coaster top to allow it to more easily flex and complete the circuit.
[Jeremy] states that at present the coaster only lights up when the glass is closer to full, but suggests that this could be useful in restaurants to notify waiters at a glance when beverages are nearly empty. If you’re looking to build a coaster that tells you when your coffee or tea is at the perfect temperature, look no further.
[Thanks for the tip, Jeremy!]