3D Modeling

In order to make things from either 3D printers or CNC routers/mills that have 3 or more degrees of movement, you need a 3D model.

While your first experience with one of these machines may use an existing test model or one you've downloaded from a site like Thingiverse, eventually you may want to create things of your own.

Here is a somewhat out-of-date list of some free 3D modeling applications: 25 free 3D modeling applications

The general workflow for 3D modeling and printing is: model the part, turn it into instructions suitable for the machine you're using to make the part, then feed the instructions to the machine and fabricate the part.