Electrons are new viewed as something like little fuzzballs rather then solid marbles. If you don’t keep them tightly contained, they tend to puff up. I dropped a mason jar full of electrons once, and it was a mess! They all swelled up to the size of tennis balls (still fuzzy) and covered the entire floor of the lab up to the height of the windows. The windows blew out, and they spilled out into the courtyard and burned the lawn, before they eventually floated up into the air and drifted off.