https://qz.com/1268647/elon-musk-says-a-fluff-bot-showed-him-the-folly-of-teslas-quest-for-a-fully-automated-car-factory/

Tesla tried to make its Model 3 factory line the most efficient ever built. Instead, it was derailed by fluff.

“We went too far in the automation front and automated some pretty silly things,” said CEO Elon Musk on a May 2 earnings call. Musk explained that in a design meant to dampen engine noise, Tesla workers were putting “fiberglass mats”—which Musk called “basically fluff,” presumably fiberglass insulation on the battery packs inside the cars. To save some time, they built the “fluff bot,” an overly complicated mission which became emblematic of Tesla’s misguided mission to automate everything at once.