Artist Andy Warhol canonized them. Comedy writer Michael O’Donoghue and fashion designer Todd Oldham collect them. They’re paint-by-number paintings, those kitchy Parisian cafe scenes and sad clowns that can be had for as little as $1 at your local yard sale and flea market. While collecting these irresistible objets d’art has been a fad for a while, doing them has become the cool pastime for anal-retentive artistes. ”There’s been a surge of interest in the last couple of years,” says Phillip Retzky, owner of Little Rickie, a campy toy store in New York’s East Village that counts members of the Hell’s Angels among its paint-by-number clientele. With more than 100 designs available from several companies-such as a 2′ by 3′ Last Supper for adults (”Great for groups of people to do on a summer vacation,” suggests Retzky) to Big Bird and Batman for kids-it’s not hard to see where the fruit of all this creative labor will end up: as collectibles at yard sales 20 years from now.