I've come across those in my searching before, they are very cool! There is a guy on YT that did a CNC wire cutter for cutting sculptures out of big blocks of granite.

For my application (wooden puzzles), the kerf is essential to be ~0.2mm so I can't use this. The 50m blade length won't be all in one stretch, it is unwound off a spool and wound onto another; though that is a great/funny sight to imagine