3D "printing" actually refers to the gradual build-up of heated plastic filament in very thin layers—usually just .2 millimeters thick. Filament comes on spools that feed into the 3D printer's extruder, which is similar to the tip of a glue gun. The extruder typically reaches temperatures of 400–550°F to melt the different types of plastic filament. The tiny layers it creates stick together to form a solid object.
Build Space: 11 inches by 11 inches by 9.8 inches high
Accepted Files: .stl and .obj
Cost: $1.00 per use and 5¢ per gram of filament used
If you want to give 3D printing a try, you can either start with your own design or use someone else's (as long as it is meant to be shared—Creative Commons). The resources linked below are free to use or offer free options. Create an account of your own to use them.