“The current atmosphere above a mountain in Hawaii contains about 400 ppm of Carbon Dioxide. This number is extremely important to all that live on the planets surface. We are surrounded now by either deniers of this worry or those who wring their hands in a flurry of agitated concern. But this number and the thousands of numbers that follow it in the news are hard to really comprehend on a daily basis. What is the amount of CO2 around me? How can I relate to this idea of gasses in the atmosphere causing overheating of the planet? For those interested I have built a Giant Analog CO2 meter that with the help of a 4 foot long needle will enliven this discussion of any school room or museum on how CO2 is measured and how you can become a part of this gas analysis.
From my work with analyzing the gas mixtures in snorkels: https://www.instructables.com/id/CO2-Measurement-in-Snorkels/ and the fun of producing giant tide clocks: https://www.instructables.com/id/Giant-Tide-Clock/ I have repurposed the CO2 sensor and the sturdy servo mechanism to make a wall mount Analog CO2 meter that very accurately portrays the current level of CO2 in the air. Most of the build is 3D printed and it also offers an accurate digital output from the Adafruit feather E - Ink display. The Air sniffing horn of the sensor enclosure is the wonderful STL file from: Resize 3 inch Spiral Speaker box by iiime that was originally done for the Nautilus speaker enclosures. It runs on rechargeable batteries or wall warts of 5 volts and will record all of your data to the included SD card holder.”