MerMar Designs.

The Temperature Candle is a relatively simple design which essentially boils
down to a 8-pin microcontroller, a temperature sensor and voltage reference
and a RGB LED on a 1.5″ diameter PCB – the same size as a standard votive
candle. The micro flickers the LED like a candle at a color determined by
the ambient temperature. The color gives an indication of the room
temperature in reference to the recommended sleep time temperature for
babies to reduce the risk of SIDS (Sudden Infant Death Syndrome).

The candle can also blink the temperature by pressing a reset button on the
PCB.

This should be a relatively cheap kit and it uses all thru-hole components
so it should be easy to assemble.  Using a simple micro, it can also be a
good introduction to microcontrollers, and is designed with a jack to
connect to Microchip’s Pickit 3 programmer / debugger.

You can see more information and look at all the design files on its project
page