The Smithsonian Institution’s Digitization Program Office uses 3-D scanning and printing technology to create replicas of artifacts that may be too fragile or precious to model in other ways, such as President Abraham Lincoln’s life mask. (Courtesy of the Smithsonian Institute)

The name “3-D printing” may seem like a misnomer when you learn how the burgeoning technology actually works. Objects are basically built from the bottom up by “printing” a succession of flat layers, each on top of the other. Here’s a basic guide to how the technology works:

Step 1

The schematic of an object is created as computer file using computer-aided design, or CAD, software, specifying the height, width and depth of the object, as well as other physical attributes. The more complex the object, the larger the file.

Step 2

3-D printing software then reads the file to determine the look of the final product and cuts the file into “slices” for the printer to produce. You then select the raw material that will be used to make the object. It serves as the printer’s “ink.” Current machines can use any number of materials, including various plastics and metals.

Step 3

Objects are built or “printed” in layers, starting at the bottom. Imagine, for example, stacking a deck of cards one on top of the other until you have a complete set. 3-D printing works in a similar way.

Some processes use a laser to fuse powder together into a desired shape. Others heat a thin strand of material and distribute it in a manner similar to a hot-glue gun. The material is then quickly cooled to maintain its shape. Depending on the size and sophistication of an object, printing can take several hours.

Step 4

When the printer stops, you’ve got the object you designed. The precision and strength of the final product will vary depending on the quality of the printer and the material used. Some objects may need to be treated with chemicals or other processes to obtain a polished look.

— Steven Overly