You’ve heard about personal 3-D printers, seen themonline and even laughed about them on a popular TV sitcom.

Now you can actually see them in action.

Demonstrations of a personal 3-D printer that copies and creates three-dimensional plastic items are now available at eight Office Depot stores in Broward and Palm Beachcounties.

But you’d best call ahead: It takes more than 40 minutes to print even a small plastic part such as a rook in a chess set or even a small bracelet. Demonstrations are at a customer’s request.

Boca Raton-based Office Depot and its Framingham, Mass.-competitor Staples are the primary U.S. retailers for printer-maker 3D Systems in Rock Hill, S.C., one of the inventors of the technology.

Staples added 3-D printers for sale online in May and now has them available in 200 stores nationwide, said spokesman Mark Cautela.

Office Depot launched online sales in mid-August and this week began printing demonstrations in selected stores to generate interest.

The entry-level Cube model sells for about $1,300 — at both retailers — and the more advanced CubeX goes for about $2,500 at Office Depot. The printers have tablet-like touch screens with more than 15 color options.

A 3-D printer uses a computer design to build an object by piling layers of material — in this case, plastic — until a three-dimensional shape emerges.

“We’re seeing a tremendous amount of interest from consumers who have read about them,” said Joan Sparks, director of marketing for Office Depot’s copy and print services.

Or perhaps they’ve seen a 3-D printer in action on CBS’s “Big Bang Theory,” where the ultimate nerds buy a 3-D printer to make toy dolls of themselves. More advanced 3-D printers are even being used to print out prosthetics, according to recent reports by CBS News and Forbes magazine.

Office Depot, which declined to give sales numbers, said it sees small businesses as its primary market for the specialty printers. Small firms are mostly using 3-D printers to do “fast prototyping” of new products, Sparks said.

The office-supply stores are selling what are considered “personal” 3-D printers, which are not advanced enough for manufacturers and other businesses doing research and development, said Mike Pomper, owner of The SolidExperts, a 3D Systems retailer in Fort Lauderdale.

Most of the more-advanced 3-D printers it sells are in the $100,000 to $200,000 range, he said.

For those customers, “the primary purpose is R&D leading to a lower cost of producing a product and do it confidentially,” he said.