He used Jell-O and cornstarch at first, but the squashy gunk, poured into a vinyl bladder, was too heavy to move. And it began to stink after a few days. Then he tried water. “Rancid Jell-O Led to First Water Bed,” a newspaper headline proclaimed at the time.

It was 1967, the Summer of Love, and Charles Hall, a student at San Francisco State University, was experimenting with flotation furniture, as he called it then, for an engineering class. (He got an “A.”) The following year, after some tweaks, his eight-foot-square heated “Pleasure Pit” debuted at a gallery on Leavenworth Street, as part of a show called “The Happy Happening.”

Mr. Hall was living in Haight-Ashbury, in an apartment in a listing Victorian that rented for $67. It was August, a slow news cycle, Mr. Hall recalled, and the Pleasure Pit made news around the country.

It was Mr. Hall’s idea that the contraption was both bed and chair, the only piece of furniture you’d ever need. Mattress companies rebuffed him in those early days, as did department stores, so he sold it himself, using his Rambler station wagon to deliver beds to local head shops, a member of Jefferson Airplane, a Smothers brother (he can’t remember which), a nudist colony (which bought two) and, inevitably, Hugh Hefner, who ordered one for the Playboy Mansion, upholstered in green velvet.