What's the story on Eggliners?

Right after I got into this hobby about a year and a half ago--all primed to see & build realistic-looking stuff--I happened across chitchat re the Eggliner. I'd seen 'em on eBay and just passed on, figuring, "Huh, toy train. Never be seen in LS modelling." I was wrong on that one. Someone even built Eggliners from other pieces, so I assume they're long out of production. So, what were the Eggliners? A fad? Something neat 'n different for the jaded? Since things are a little slow, this won't take up space.

Les