Our two favorites would have to be GoogleSketchUp and OpenSCAD. OpenSCAD is completely free and has a solid base in CAD modeling. OpenSCAD is a bit more complicated than Google SketchUp, when it comes to a learning curve, but you can do some amazing things once you learn how to use it
correctly. In addition you’ll gain a bit of programming knowledge on your journey. But don’t be intimidated, making everything work together isn’t all that hard once you dive into it. The great thing is that there are plenty of documentation/tutorials to help you on your way. You can get some inspiration and possibly some help accomplishing your learning goal by checking out Thingiverse (Anything tagged customizer = OpenSCAD).
Here are some models and ideas from one of our co-founders, Greg, made using OpenSCAD and Thingiverse’s customizer application. You can always download the OpenSCAD files from pre-made models and modify them to suit your needs.
Google SketchUp, our first choice when modeling something, has a free version, SketchUp Make, and can be used for most anything you can think of.
Google has also set up some free tutorials on the subject. The tutorials are a bit involved but once you have SketchUp under your belt you’re well on your way to becoming a modeler extraordinaire! Both of these tools have their strengths and weaknesses, but together there really hasn’t been something we were unable to design rather quickly for a 3D printer. Here’s a Google SketchUp design Greg made for a Roll-Out Pantry.
We hope you enjoy making as much as we do.