Interestingly, I've seen the equivalent of this on the low end - workers in third-world machine shops or electronics recycling places with an opaque block betwe

Interestingly, I've seen the equivalent of this on the low end - workers in third-world machine shops or electronics recycling places with an opaque block between them and the workpiece, with a cell phone and its camera slotted into a cutout. Just look at the phone screen, not the workpiece.