The thermosensor is located in a drilled 10mm hole in the wooden board right below the mixer tap. In the video it is intentionally not shown, not to destroy all the magic…
I choose a thermosensor with the narrowest beam I could get, this one has a FOV of only 10°. That allows it to cover the whole stream of water. I think this a prerequisite for accurate and non fluctuating measurements. I expect it would be difficult to measure the temperature of the common smaller round streams from this distance.
As always there is room for improvment. On the stills at the beginning of the video you can see that the corners of the sandblasted acrylic glass are a little bit darker then the rest. I will try to make the leds sitting directly at the corners a little bit brighter.
And now that it is in use, new features come to my mind. If you are taking a bath some other light effects like e.g. a fire simulation may look nice as an ambient lighting.