I was expecting different click-bait, like a keyboard drawn on paper with a camera pointed at it or something.

Me too, and probably possible as hack that any decent developer can do right now.

In fact when camera enabled glasses looked like they were going to be a thing that was the very thing I imagined taking off. You grab a piece of paper and haphazardly draw a bunch of keys on it and your glasses with a little AI do the rest

How about a laser-projection bluetooth keyboard?

https://www.youtube.com/watch?v=xmKdtAePxy8

They've been available for a few years now.

Fun fact: they've been available for over a decade at this point. I wouldn't be surprised if it goes back a few years more than this 2008 article. Never personally used one, though.

https://www.geeky-gadgets.com/geeky-gadgets-the-bluetooth-la...

Ain't great. You can only type certain keys at a time since the beam-break for j prevents a follow-up n in the denounce period. I only get about 30wpm... Disregarding feedback.

It could probably be done now just by looking at hand shapes and if you’re a touch typist you might not even need the projection, just a dot or two (which could just be stickers on a surface) to orientate your hands over nothing.

Hand shapes for typing are far from standardized or recognisable. Nowhere near the accuracy a laser beam break gives you. (The projection LED is separate from the detection laser, which is much lower power)

Well, to be honest, the ability to print useful circuits onto ordinary paper and have a working electronic thing made of said paper in minutes is pretty cool...

I had imagined they had built it by carefully folding the paper to give each "key" a distinctive sound that a nearby computer could decode into key presses

Were you expecting magic?

I went in expecting some sort of clickbait (since, y'know, paper isn't exactly known for its electrical properties), but I'd assumed that when they said "[w]ith a simple piece of paper" they really meant a piece of paper. I expected it to be "with just a simple piece of paper an a $14k sound analysis / SDR / magnetism detection rig, we can detect force on the paper", which is still clickbait but would've at least struck me as interesting/novel, as opposed to "we layered actual electronics on paper", which could be interesting if they're pioneering flexible electronics or something but makes the paper basically irrelevant.

> with just a simple piece of paper an a $14k sound analysis / SDR / magnetism detection rig, we can detect force on the paper

This is actually better than that. They created a spray on invisible circuit board that can both detect touch inputs and generate enough electricity to power a bluetooth radio. They achieved all this for a unit cost of 25 cents. That's a pretty amazing achievement and opens up some quite practical uses.

Imagine something like Nintendo Labo, but with so many more opportunities for interactivity.

Another idea, imagine a student's notebook that synchronized their writing with their phone.