Axis that is not x, y or z

I want to build a pyramid out of plywood. I can draw it using Sketchup easily enough. But to cut the plywood pieces I’ll need to create a 2D drawing of the face of the pyramid. How do I change the axis so I’m looking directly at one of the faces of the pyramid?

I’m sure this is easy but I’m a SketchUp newbie.

Try right clicking on the face and selecting align view.