I wonder if they just used a custom slicer. In undergrad, I wrote my own slicer and used it to do silly things (less "can I make this?" than "What would happen

I wonder if they just used a custom slicer. In undergrad, I wrote my own slicer and used it to do silly things (less "can I make this?" than "What would happen if?"). I would imagine they took a similar (though, obviously, much more intelligent) approach here, just thinking directly in terms of slicer features, rather than in terms of models.