[disillusioned]

Aren't the current fingerprint scanners ultrasonic rather than optical? I think they rely on the actual physical ridges

[Nexxxeh]

The process uses the depth of the toner layer to make a mould of the physical ridges, which you use to generate a a gelatine cast of them. It's like a single-layer depth 3D print where the medium is fused toner from the laser printer.