A common question from new CNC software users is, "What CAD program do you recommend?" As you might guess, the answer is, "It depends". Here is a list of the best deals in free or inexpensive CAD programs.
One quick note, if you're a Mac user then check out our list of 3D CAD programs for the Mac / OSX.
3D modeling programs are used to make models for animations or video games and those models are never meant to leave the computer. These programs will let you design complicated shapes easily but they can make it more difficult to design mechanical shapes to exact dimensions.
Blender (Free) - Blender is a free, open source 3D modeling program. The interface is very non-traditional and will require some adjustment if you've got experience in a more traditional 3D design program. Amazon stocks a ton of books about Blender so it should be easy to find some material to help you out.
Silo3D ($99-$159) - Silo3D is a subdivision modeling program that, like Blender, is not primarily targeted at users trying to design models to be machined. It is incredibly powerful and the interface is easier to learn than Blender. This is a great value if you're looking to model organic shapes. The big downside here is that it doesn't export STL files natively. You'd need to use another program to convert from OBJ to STL.
Free form CAD programs let you design dimensionally accurate models but don't impose any structure or workflow on your methods.
Sketchup (Free or $500)- Sketchup is a CAD program that was originally targeted to the architectural market. It is a very simple program to use but it isn't well-suited for organic shapes. In 2006 is was acquired by Google and a free version was released. The free version will not export an STL file but several people have written plug-ins that allow Sketchup to export an STL without paying for the full version. The various approaches are discussed here . You can also buy a commercial STL exporter from sycode
Viacad 3D ($99)- Viacad is a simple , powerful 3D CAD program. It isn't as popular as some of the others here but it's inexpensive and you can get up and running quickly. It is available for Mac and PC, making it unique in this list.
MoI ($295)- MoI (Moment of Inspiration) is a 3D CAD program that was designed to be usable on tablet or pen computers. Because of this, the user interface is simple and doesn't require a lot of typing. It was written by a single guy, who was one of the original developers of Rhino, so it's powerful without being bloated. It is equally well-suited to organic or mechanical shapes. Without a doubt, this is one to try.
Rhino ($995)- Rhino is one of the most powerful and flexible CAD programs anywhere. It has every kind of tool you could need and , like MoI, is equally well-suited to organic or mechanical shapes. It isn't inexpensive but it does almost anything you could need. If you happen to be a student then you can get a significant discount. Version 5 will also be avialable on Mac OS X when it is released.
Parametric CAD programs keep the entire history of the model as it is being built. If you find the need to change a shape or dimension then you just go back in the history, make the change, and the model will be rebuilt automatically. If you make a big change then you may have to do a little work to get the model rebuilt properly but it's still going to be faster than a program like Rhino. Parametric CAD programs are incredibly powerful if you are willing to spend the time to get your head around the workflow.
OnShape (Free - $80/Month)- OnShape is a new cloud-based CAD program from the same team that created Solidworks. It runs completely in the browser so it runs on PC, OS/X or even an iPad. There's a range of pricing options and for many users, it's totally free.
Alibre / Geomagic Design ($199- $1400)- Alibre is a very powerful parametric CAD program that is available for very little money if you only need to export to STL. They take a lot of pride in the fact that you can do 99% of what the very expensive programs can do at a fraction of the cost. As a comparison, Solidworks, one of the most popular programs in this category, will cost you a minimum of $3500 to buy it and $1200 a year for updates. The $99 version of Alibre is the most amazing deal on this page.
Although it's in no way a low-cost program, Solidworks works very well with MeshCAM and it's very popular with MeshCAM users. Just in case you're one of them, we've got a Solidworks CAM page with some instructions to help get you started.