Why is this any more absurd than a shower cap?" asks Howard Smith, adjusting the zippered cone on his chin. Devised decades ago to keep whiskers dry while bathing, the cone is covering Smith's fake beard and his widening grin. "So it's not the best invention ever," he concedes. There have been worse, as Smith knows better than almost anyone else. To make Gizmo!, an 80-minute film documentary about crazy inventions, Smith and 22 researchers examined thousands of old newsreels in which tinkerers demonstrated such brainstorms as a dimple machine ("Clamp it on at night; wake up looking like Shirley Temple") and a set of car-seat dummies ("so you won't feel guilty driving past hitchhikers").

Not all the film clips are funny. Early flying machines sent their pilots hurtling off cliffs, and submarines didn't surface. "The smart inventor is the one who gets somebody else to test his product," Howard suggests. In choosing the 300 clips from 10 countries for the film, Smith rejected one showing a man wearing huge fabric wings plunge off the Eiffel Tower to his death. "You include that," says the filmmaker, "and people stop laughing for 20 minutes."

Smith admires the gadgeteers. "These people were brave enough to go out and do something," he says. "There are probably inventions that could have changed the world that people kept to themselves."

As a teenager in Newark, N.J. (where his parents owned a cigar store), Smith invented a tennis shoe detergent, children's fortune cookies and an ice-cream stick made out of candy—none of which made him a lick. Instead he dropped out of Pace College after three months to write poetry. He went on to sell antiques and host a syndicated radio show, interviewing "everyone from Margaret Mead to Twiggy." He claims to have originated Playboy's "sex polls" and writes the Scenes column (mostly "sex and drugs") in New York's Village Voice. His first film, Marjoe, about a cynical evangelist, won Smith and co-director Sarah Kernochan an Oscar for "best documentary." Next Howard plans a horror movie, if he can find the right script among the more than 50 a week he reads in his Manhattan loft.

Not surprisingly, Smith, the divorced father of two sons, hasn't had time to develop any of the likely ideas he turned up in Gizmo! "A good idea isn't enough," he says. "Marketing has a lot to do with it. I can see some of them taking off—but only with Gloria Vander-bilt labels."