Deep in a sub-basement of the GM world headquarters, dozens of high-tech machines emit a soft whirring sound. In a sandy liquid, as an arm passes quickly overhead while a model slowly emerges. It’s the side-mirror of a new concept vehicle with a place to insert the mirror and bolt the part into place.
This rapid-prototyping room runs all year long, every day, seven days a week. The machines never quit. Designers make dozens of “first run” models that are fitted with other parts. For example, when Chevy designed the Volt extended-range car, they used rapid prototyping to create many of the parts. (In a pinch, they even used a plastic part intended as a model for the initial road-testing.)
While rapid-prototyping is common with large automotive firms, similar techniques are used by hobbyists and professional designers at home. Using a 3D printer, they create a design and, with just a few clicks, produce a physical model. Many 3D printers can be used to generate hundreds of these models, and some companies even let you design and print your own models on the Web.
One reason 3D printing is becoming more popular is that the alternatives are still so expensive. Injection molding machines, which are used to create everything from pens to fenders, cost millions. It’s still true that, if you want to go to a design shop and have them create an injection mold of a plastic part, the design and production costs will be around $10,000 for just one part. Meanwhile, a 3D printer can produce the same part for only $2 or $3 – and many 3D software programs are free.
“3D printing provides an object with which the designer or customer gains a sense of reality,” says Steve Beaudet, a training specialist with SolidWorks, a company that makes 3D design software. “On the manufacturing side, 3D printing can be used to test how parts fit together to check clearances and mechanical motion. People create prototypes because the scale is often hard to envision on a computer screen. Holding a 3D printing piece in your hand tells exactly how big it is and how it feels.”

The basics: Software and hardware

3D printing starts with the software, says Rick Pollack from The programs he typically recommends are Google SketchUp (, OpenSCAD (, and Solid Works ( Another application called Skeinforge ( slices up the data into printable chunks. This app produces the code that’s used to send commands to the printer, and another program called RepSnapper loads the code and controls the printer.
Using the software, you first design an object you want to print. This can be as simple as a butter knife or as complex as a ship, but the process is roughly the same: You set the coordinates for the design and then send the coordinates to the 3D printer, which uses a substrate material to sculpt the model.
MakerBot Thing-o-maticThere are several options when it comes to 3D printing kits. Pollack offers the MakerGear and Makerbot kits. The kit is another low-cost way to build your own 3D printer, and once you have assembled the 3D printer at home, you can then use the printer to create a second model.
“The best software suites out there for designing are probably Solidworks and Autodesk Inventor, which are used by engineers and usually run about $3,000 per license,” says Enrique Muyshondt, the president
of desktopFab (, a 3D printer company based in Texas. “There are other options, though, including the recently released Autodesk 123D Software ( that provide a good, easy-to-use, and fairly intuitive design interface for free.”
A commercial product from 2Bot called the ModelMaker ( costs between $9,000 and $12,000 and comes with all the modeling software, called 2Bot Studio, and video training you need. One key difference between a commercial 3D printer and one you assemble yourself is that the kit is typically designed for the non-expert to get started right away. For example, the software can load models from Thingiverse ( and the Google 3DWarehouse ( ).
“We have had children as young as 7 make models and print them on the ModelMaker,” says Darren Coil, a 2Bot vice president. “These tutorials can get one up and running in less than 15 minutes.”
Another difference between a commercial 3D printer kit and the ones you build yourself like the RepRap is the cost of materials. Coil says one model printed on the ModelMaker will cost just $1 for the material, but do-it-yourself kit materials are much more than that – up to $20-$50 for one model. Another advantage he says is printing speed. The 2Bot prints about twice as fast as home DIY kits.
3D_scanning_and_printingPollack says one of the most common uses for a 3D printer today is creating toy models. For example, hobbyists will create a new design for a miniature train as part of a complete set, then print out all of the parts required, assemble them by hand, and paint the finished train.
Note that, one final step in the 3D printing process involves curing the model. In some cases, the 3D printer itself will take care of this, but home kits usually require that you use a curing chamber or a chemical bath to solidify the print and prepare it for handling.

3D printing trends

One of the key trends with 3D printing is that the costs are finally going down. Muyshondt says the hardware and production costs are now about one-fifth what they were just a few years ago. 3D printing has not exactly gone mainstream – not everyone has one sitting next to their HP 2D model yet.
“There seems to be a real push in the last few years to make the printing systems more affordable, allowing for smaller shops or individual consumers to do their own prototyping,” says Beaudet. “Desktop units with lower capital expense systems have recently become available. Some of these smaller units require more manual process steps and sometimes a few extra components (beyond the actual build machine) to complete the model. However, if the price point is right, it works for some.”
Another trend has to do with replacing broken parts – even in your own car, a hardware product in an office (say, a plastic arm in your 2D printer), or a plastic part in a child’s toy.
“If you need to replace a broken part or need a custom-made object of some kind, 3D printing allows for access to an inexpensive personal manufacturing solution that otherwise would have cost many hundreds or thousands of dollars through traditional manufacturing methods,” says Muyshondt.
One of the most interesting trends, though, has to do with services on the Web that will take your finished model, print it on a 3D printer, and send you the results. This homebrew approach means no complex setup, no messy materials, and no curing once the design is printed. is one of the leading companies that provide this service. You submit your model, choose the size of the object and the material used, verify the final mock-up, and print. In a few days, the final model arrives in the mail. Sculpteo also offers a bobble-head service where you take a photo of your face from the front and side, submit the file, and print the bobble-head.
bobble heads 3d printing
Clearly, 3D printing will not replace rapid prototyping at a large company or be used for serious parts production. However, there is a possibility that 3D printing could expand well beyond home hobbyist production. One early indicator of this is that, for the ENV concept car that GM built last year, many of the parts were made using 3D printers and rapid prototyping.
In the future, it’s easy to envision that someone working at home could decide to “buy” an ENV from GM, but print out all of the parts at home and assemble them. They could customize the colors and even the parts – say, making their own custom fender that’s different from everyone else’s on the road.
In 20-30 years, it may even be possible to print just about any custom object – your own toothbrush, a new faucet for the kitchen sink, or a new dashboard for your Buick. We’re in the same phase with 3D printing that Steve Jobs was in when he designed the basic components of the Apple computer in his garage. The next step is to show non-hobbyists that 3D printing is a legitimate activity.
(Top image courtesy of aigarius.)