Awesome project. But $300 is still quite steep for a thing I might maybe use once a year. I really wish these thermal sensors came down in price...
The sensor itself is 160. There is no getting around that.
you could make your own thermal sensor, which is what i thought the article was going to be about from the title
this is a bit like 'i made a working, drivable car from scratch using only basic hand tools, raw materials, and a 2005 honda civic' or 'i built my own operating system around the linux kernel'
https://github.com/google/skywater-pdk
One could make an array of thermopiles, like the hacker that made their own imager out of discrete diodes (digiOBSCURA) . But each pixel would cost $7.
https://www.digikey.com/en/products/detail/excelitas-technol...
One might be able to make an array of thermistors (possibly with active cooling using a peltier) like the diycamera (digiOBSCURA) below. Might be an application of combining many RC oscillators in a tree and recovering the signal with an FFT. I have a gut feeling this is possible, but haven't show it. Isn't this the same as or similar to your keyboard multiplexer design?
https://www.digikey.com/en/products/detail/panasonic-electro...
https://github.com/IdleHandsProject/diycamera (digiOBSCURA)
One could experiment with microbolometers on tinytapeout. https://elicit.org/search?q=cmos+microbolometer