On a completely different note - 3D printing...

For Christmas I bought myself an anycubic Kobra 3 Max, with the "ACE Pro" unit for filament switching, etc... had the first case where the automatic filament swap was used yesterday... it went very smoothly, with one slight hiccup...
When they spool the filament, they typically will either tape the inner end to the spool, or they will bend the end so that it doesn't come out... This will prevent the filament from releasing from the spool at the end, so instead of the system realizing that it has reached the end, and automatically switching to the next spool, it realizes that it has a jam, and needs intervention

a quick clip with the cutters, and it then used up the last bit, and auto-swapped.

Maybe that's why they use the cardboard core around the plastic spool... so that you can get in ahead of time to clip the end?