Rapid Prototyping With CNC Tools

Authour:Alex Leitch
Edited by Christine Keene


Rapid prototyping with CNC tools is a continuation of the sketch processes to develop a physical product. Although 2D and electronic sketch processes are commonly used to iterate software product designs, they are less commonly used in physical product design due to the historic expense.  That expense has recently dropped, allowing artists and architects to join mechanical engineers in the use of CNC tools.

CNC stands for computer numeric control. Rather than carving a prototype by hand, a design can be programmed into a calibrated machine and a prototype will be created on-site.  This is beneficial as iterations can continue before committing to a production run on a conventional platform (Wired.com, “The Age of Desktop Manufacturing.” 2012).

The use of advanced tools like desktop 3D printers and inexpensive laser cutters allows a high level of detail. The product can then be iterated and mass-produced from original computer sources, which do not tend to suffer random variation as hand-finished models do. This allows collaborators to repeatedly work on the same base models together, or print their own variants.  It limits the reliance on the hand of the designer and speeds the product development cycle. This allows for a more evolutionary design practice.

CNC based rapid prototyping comes after sketching in the design process.


CNC prototyping evolved out of the same techniques first developed in the early medieval period (Buxton 2007). It works on the principal that all but the finished product can be thrown away, but it also implies a value to the object itself that invites use.


This technique is performed in order to:

  • Assess functionality of concept piece;
  • Assess overall real-world design quality; and
  • Determine unexpected production costs, for example: parts that will break off or triggers that appear useful on paper but are unworkable by specific demographics (i.e. elderly) in the real world.

Goes By

This technique is also called: prototyping or modeling.


Modeling by hand or prototyping in paper are very similar to rapid prototyping for manufacture. They allow people to experiment with the design before having the finished product in hand, allowing for a better quality of finished product.

Using The Technique

Rapid prototyping using CNC tools requires some investment in high tech resources. The first requirement is a computer, and then a suite of Computer-Assisted Design software.

You Will Need:

  1. A computer that is less than seven years old.
  2. Software, for example: SketchUp, Autodesk’s Make suite, Blender, Rhino, Inkscape, Illustrator, Photoshop, or GIMP.
  3. Version control software is handy, or a version control plan, so parts that work can be kept and those that do not can be discarded.
  4. A sketchbook.
  5. Access to various CNC output devices or access to an output shop, such as TechShop, Shapeways, or Ponoko.


  • A clear sketch of the prototype is required.
  • It is useful to have the prototype split it into each of its moving parts, so the pieces can be assembled.
  • Model each of the sections of each part.
  • Output sections to the appropriate CNC.


  • A full prototype of your design, of which some parts will be instantly useable.

Next Steps After Exercise

  • Iterate the prototype that has been produced.
  • See where it breaks and why, take notes. Are the wings too heavy? Do the doors not shut properly?
  • Go back to the 3D software models and adjust accordingly.

Other Points of Note

Rapid prototyping is not actually that rapid, it is simply faster than it has been historically.  New materials and techniques allow a prototype to be created and iterations to be integrated faster.

It is very helpful to have access to a design team. Collaborators can include technicians, much as reproductions of paintings once relied on skilled engravers and lithographers to get the prints right.

Many people who use this technique artistically focus on bizarre, algorithmic shapes that could not be produced by hand.

Unfortunately, by removing the hand of the artist, individual objects produced using a rapid prototyping process lose individual value. They are limitlessly reproducible, identical, and require only the correct manufacturing setup to make. Once source files have been created and released, your work no longer requires you. How you add value – get paid for your work – on top of the basic model is up to you.

Case Studies and Examples

3D printing is commonly used in dentistry to get truly excellent tooth fit (Wired.com).

The Evolution of the OrangeX Manual Juicer is a case study from Buxton’s 2007 text Anatomy of Sketching Experience Design (http://billbuxton.com/).

Makies (http://makie.me/), a doll manufacturer in England, uses these techniques to fabricate one-off custom dolls via online ordering.

Anderson, C. (2012). The New MakerBot Replicator Might Just Change Your World. Wired. Retrieved from http://www.wired.com/design/2012/09/how-makerbots-replicator2-will-launch-era-of-desktop-manufacturing/

Buxton, B. (2007). Sketching User Experiences: Getting the Design Right and the Right Design. Burlington, MA: Morgan Kaufmann Pulbishers.

Hart, G. (n.d.). Rapid Prototyping Website. Retrieved from http://georgehart.com/rp/rp.html

Shapeways 3D printing house. (n.d.). Shapeways. Retrieved from http://www.shapeways.com/

Stratasys. (n.d.). Digital Dentistry. Retrieved from  http://objet.com/industries/dental/