Battered booksellers, especially independent ones, have so far withstood the punishing shock-and-awe offensive of Internet Age marauders like Amazon. Now, they have a secret weapon that they hope will continue to lure customers into their stores: would you believe it's a machine that can print up a fresh new paperback copy from a menu of 3.6 million books?

Harvard Book Store cleared out space behind its History, Politics, and Religion sections to make room for the three-foot-by-six-foot-by-four-foot robot retailer, called the Espresso Book Machine. In a public unveiling slated for September 29, the Harvard Book Store will become only the second US merchant to install such an apparatus, which prints, binds, and trims perfect-bound books — complete with full-color covers and black-and-white guts — in about four minutes.

"Books will be produced on a massively decentralized way," promises Dane Neller, CEO of On Demand Books, the manufacturer of the machines that will let customers select from millions of titles in less time than it takes to comb the teetering stacks of a used bookstore. "The life of the book will be infinite."

Says Harvard Book Store owner Jeffrey Mayersohn, "I had developed a notion that the ability to produce books in stores was an important part of the future of bookselling."

So is having access to an inventory that rivals the depths of the Amazons. With the machine comes a deal inked this month between Google and On Demand Books, which gives patrons access to more than two million public-domain and out-of-print titles in Google's digital coffers, coupled with 1.6 million others. "We're moving steadily toward the goal of any book, ever written, in your hands, in a moment," says Mayersohn.

With production and order fulfillment gone local (and Harvard adding its own bicycle-delivery twist), this could be a leaner, meaner, and greener economic model than centralized book production and distribution with the biggies — but only if enough readers demand sufficient obscure titles, at $8 a pop, to pay for the $100,000 machine.

"I personally don't know how far this is going to go and how much the economics are going to work for the booksellers," says Tom Hallock, associate publisher and sales and marketing director of Boston's Beacon Press. Nonetheless, he says it's important for brick-and-mortar stores to stay in the game: "I applaud the Harvard Book Store for bringing in the machine and seeing what they brew up with it," even if in-store printing competes with trade publishers like his.

Perhaps the model's savior will be self-publishing: folks who want their poems, grandma's recipes, or Great American Novel printed in a professional package. Would-be authors can print a few copies, see how they sell, and produce more, making small press runs feasible. Not that printing is the same as publishing with an editor and ISBN. But Mayersohn says the self-published won't be ghettoized. "We haven't ruled out the possibility that you print your book with us and we'll put the book on our shelves," he says.

And with that, a hint of immortality. "Once a book is printed, it will be in print forever."

For more info on the Harvard Book Store event, go to harvard.com/bookmachine.