Since I'm unbound by the generic requirements of "the masses" and have complete idea freedom until "the rubber hits the road", as they say, I was wondering about any additional features I could install into Leti. The requirement was that:

1. it had to actually be useful, and
2. it needed to fit inside the space available, as well as not being possible to do in a smaller form factor by using a phone.

Those 2 points eliminated the first round of ideas, such as a high FPS camera, 360 degree camera or infared camera. The first point stopped me from considering a pico projector, which happens have existed in quite a handful of phones actually:

I thought there was only 1 .

Anyway, I then thought back to when someone made a reddit post in r/framework about "dumb" expansion bays, where I suggested an A4 doc scanner. This is the humble pocket scanner I owned way back in 2018 or 2017:

It broke almost a year after I bought it, but it allowed me to get nice images of flat surfaces, however due to the design flaw that I'd like to address, it wasn't all that great at scanning books. Essentially, I need to get the scanner as close to the longest edge so that I can scan right up to the middle of the book. Still, it was quite fun to use, though a bit tedious since it was a seperate device that needed to be charged and you had to use a micro SD card to transfer the files to the PC and it cost something like £80 for the WiFi edition. With that WiFi edition, you'd actually need to connect to the network that the handheld scanner generated, so it's not like the workflow was all that much smaller.

The idea would be to try and use the sensors I've found for the #SecSavr Suspense [gd0105], which is MUCH cheaper than the £50 I spent on that handheld scanner.