dlloyd:
Some technical information 1/3 way down the page here might be useful for your project's R&D. Possibly replace dozens or even all pixels with one module?...
https://www.kickstarter.com/projects/grabo/gesturer-arduino-compatible-gesture-sensing-module
I need to incorporate any touch-sensing solution to my current design - a wooden grid for RGB LEDs. I don't think those modules would fit/work in that respect. The technical info does show that they use IR photodiodes and I've seen IR phototransistors used as well in other projects I've researched, both of which are a lot cheaper than the premade IC sensors I've been discussing before. I could put one IR LED and IR photodiode or IR phototransistor per cell and it probably wouldn't cost much more than $0.50. I'm not entirely sure which is most suited or what small circuit I would have to make for each cell at this stage, but it seems more promising than any other idea. It does mean it would be sensitive to background IR light from light bulbs and sunlight, however, unlike the modulated IC sensors. I think I could work around that anyway given the much cheaper price and analogue outputs (?). Thanks for pointing this out.
This goes back to multiplexing or using a bunch of multi-channel ADCs for connecting lots of analogue inputs again. Those being the two best solutions discussed so far. I also need to figure out what small IR LED/photodiode/phototransistor circuit I need for each cell. Any guidance welcomed!