Kathrin Winter carefully hangs a Christmas decoration on a fir tree standing in a pot in the corner of her store.

But the plastic stars and Christmas balls hanging on the tree are somewhat special. Instead of being made in a factory, Winter printed the ornaments herself on a 3-D printer in the 3-D store she owns together with her partner, Daniel Zimmermann.

The store, called Mr Make, opened recently smack-dab in the middle of the high street of Karlsruhe, a city in Germany's southwest.

"Most people have heard of 3-D printing," says Zimmermann, a computer scientist by trade. "But the average consumer still doesn't have a concept of what that actually means. So our idea is to make 3-D printing more accessible."

The display room is filled with diverse objects in brightly colored plastic. There is a cookie cutter in the shape of a guitar, an architectural model where each story is printed separately so it's possible to see the interior room layouts, a grinning Halloween pumpkin, replacement handles for a pair of pliers, and strangely shaped spare parts.

Each object has been created on a 3-D printer, which works by rapidly fusing together layer after layer of plastic or another material to make a solid object. But many items, such as the Christmas decorations, are still cheaper to produce in a factory production line rather than to print out.

The big advantage of 3-D printing, explains Zimmerman, is that it's possible to get one-off, personalized items on the spot.

"You can come past with the latest smart phone, and we can print a case out of plastic that has the customer's name or company logo on it," he says, holding up a bright-blue example.

"That's very individual. You always have your phone with you, so everyone can see it - and it looks great."

The ultimate selfie

Mr Make has only been open for six months. And while printing architectural models or design prototypes keeps the shop-owners busy, by far the most popular service at Christmastime are 3-D selfies in the form of a 10- or 15-centimeter-tall figurine.

To make the figurine, the customer stands in a brightly-lit round booth, where more than 60 cameras simultaneously snap photos. These images are then processed into a blueprint and sent to the 3-D printer, which prints the customer's image in a ceramic-like material.

The final figurines are an uncanny clone of the person - replete with exact clothing, hairstyle and facial expression.

A 10-cm figurine is already relatively cheap - it costs only 99 euros ($120).

And these kinds of scans aren't limited to being made only in plastic either. 3-D technology has advanced so far that most kinds of metals - such as silver, brass, bronze, gold and platinum - can also be used for printing.

For consumers, this means virtually anything's possible - like a gold wedding ring with the scanned face of your future husband embossed into it.

Feelin' it

This ability to print one-off scanned objects relatively cheaply is proving a boon to students at the Karlsruhe Institute of Technology (KIT), just up the road.

KIT - a specialised science and IT university - has a center for blind and visually impaired students, which provides people who have problems seeing with special study material and literature.

Recently, 3-D printouts have also become part of the center's services. They are now printing large-scale 3-D models of objects such a molecules for chemistry students, and complicated geometric shapes for math students - all with Braille annotations.

The blind and visually-impaired students "love working with the 3-D models," says Thorsten Schwarz from the center.

"When you have sight and you want to look at an insect eye, you can use a microscope and have a closer look," explains Schwarz. But blind students can now feel it with their fingers.

Mind-boggling array of uses

A growing number of enthusiasts are uploading open-source design files for 3-D objects to Internet sites such as Thingiverse. While there are many objects with serious purposes on the site, it also has blueprints for printing everything from a snowball scooper to extending wolverine claws and a Darth Vader cookie cutter shape.

As more and more designs go online, there are growing concerns that companies will begin to clamp down on the use of 3-D printers for reproductions of patented or copyrighted products.

"If people are not careful or clever, it might come to the point that we have similar legal battles that we see for movies or music," says Jochen Zimmer from 3-D research firm Indmatec in Karlsruhe.