Over on Adafruit, John Edgar Park latest project lights up the Halloween gloom with a rack of glowing test tubes illuminated by computer-controlled LEDs and florescent UV pigment. John writes of the project:

A proper mad science laboratory requires mysterious potion-filled test tubes lit with eerie colors to flicker in their rack. Build this display for maximum creepy effect!

Flourescent pigments mixed with water make for a creepy-cool luminescent potion when lit with ultraviolet light, especially as they flicker and blink based on a microcontroller pattern you design. You can use this technique to make test tubes glow in a standard test tube rack, or build your own from black iron pipe fittings and laser-cut acrylic for some next level spookiness!

The system is powered by an Adafruit Feather development board driving 13 UV/UVA 400nm LEDs. Besides using the lights and electronics to illuminate a test tube rack, you could also use them to light beakers and other bubbling labware or other equipment and features of your mad scientist lair.

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You could obviously just buy cheap test tube racks to display your creation, but John decided to build a suitably industrial-Gothic-looking rack out of black iron pipe and a test tube holder that he designed and 3D printed. The plans for the rack and the CAD file for cutting the tube holders are included on the project page.

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See the full details of the build and get the control code on the Adafruit Learning System.