Need a bit of CAD help.

So, at my technical school my teacher recently gave us an assignment to Create whatever we wanted, via program like Auto CAD or Solids Works. The catch is that we have to create a tutorial and a physical prototype along with it. I have the majority of my throw completed, but the problem is the axle system. I have no clue how to get started on it. Can someone shed some light on the topic for me?

As for a physical prototype, We have a Machine shop in our school that offered to make a small run for me.

Thanks!~

I know a ton about CAD, shoot me a PM and I can answer any questions.