Inigo may not have a great idea of how human anatomy works, but honestly, he'd believe it if there was some secret energy source in her hair. It'd explain how it can move and do all of those things by itself - and also why Entrapta is just so amazingly Entrapta.

"I don't know, I feel like I might pass out if I did as many things as you in one day." And even though he's smiling, and there's a joking edge to the words, Inigo doesn't mean it in a bad way. He thinks Entrapta's work ethic is something to be admired, though he isn't always sure if it's being used for the right or best purposes.

(He is, however, not lying that he'd definitely pass out. That's just too much for him to keep up with.)

"I'm half surprised you haven't managed to transform the entire train yet with the things you make." Like that robot she was making.