What is 3D Printing? – Think of 3D printing as the opposite of CNC machining: Instead of starting with a big block of material and machining out the part you need, it takes tiny bits of material and connects them layer by layer, building up the part you need. Because of this the term Additive Manufacturing is used to describe all types of 3D printing processes. Imagine a square cut out of cardboard, then another slightly smaller one cut and placed on top of it, and on and on until it came to a point, automate that process and you have a 3D printed pyramid.
How does 3D printing work? – A 3D computer blueprint file of the part you want to make is sent to the machine the same way a picture would be sent to an inkjet printer. In order to get this file you either need to draw it yourself with a Computer Aided Design (CAD) program, scan a part with a 3D scanner, or download a file from one of the various sites online for 3D printing. Then another computer program “slices” the design into the very thin cross-sections that will be printed with each pass of the printer. Now the printer can start printing 2D layers, which combined to create the 3D object. Various methods and materials are used to make the layers, depending on the machine.
What can be made with a 3D printer? – Almost anything, literally! New processes and materials for 3D printing are being developed all the time. The most common process uses a laser and various plastic filaments including ABS and nylon to produce parts as strong as their injection molded counter parts. But 3D food stuffs, and even biological materials are already being printed right now.
Can I print metal? – Printers that can print metal are still too expensive for most users, but 3D printing can be used to make a plastic duplicate (and easily adjust the scale) of an object, then a mold can be struck to cast metal parts from. NASA does have a system that can print complex parts in various metals using wire and a beam of electrons; similar to precisely MIG welding a part from scratch. There are also various methods to form solid metal parts from a bed of powdered metal particles using different heat sources to fuse them. Hopefully the costs of these systems will come down in the future to enable their use by automotive shops.
What if I don’t have a 3D printer? Can I still print custom parts? – Sure. There are several sites online that will connect you with people who have printers and or will help make parts. Shapeways (http://www.shapeways.com/how-shapeways-works) for example, allows you to upload your custom design (or work with their 3D modelers) and output them in 45 different materials, including a metallic Alumide plastic, and steel.
Can 3D printing be used for actual moving parts of a car, not just decorative trim? – Yes. Koenigsegg in Sweden has used 3D printing for all sorts of things on their super cars. From minor parts like AC duct work and side view mirrors, to critical metal parts like titanium exhaust parts and whole turbo chargers. General Electric makes parts for their jet turbines with 3D printing.
Can carbon fiber body work be 3D printed? – Not exactly, but there are companies, Local Motors (https://localmotors.com/) for one, that are working on being able to print large body and chassis parts with a fiber reinforced plastic in the near future.