Extrusions are the most basic solid shape to create in Computer Aided Design. Here, I am creating an extrusion in OnShape. I start by selecting a plane, creating a sketch, and then selecting the “Extrude” command. This lets me add volume to the sketch. All 3D volumes in CAD are considered extrusions, and this is the simplest way to create one.

OnShape also has a feature that lets you subtract volumes, which is called the “Cut” feature in some other CAD programs. To cut out a piece of an extrusion, I create a sketch and choose the extrude feature in the negative direction on the surface of the extrusion.