Mechanical engineering uni project

I'm a mechanical engineering student with a fairly open brief for a short project. Have to draw a 3D cad model of a mechanism and do some motion analysis. So i thought i'd ask the fine folk of slrpnk if they had any projects that need a bit of ironing out.

Probably best suited if you have an idea and want see how the parts might move in 3 dimensions. I'd be able to tell you stuff like how much force/torque is in a particular part, letting you know how strong bits need to be.

Has to be a mechanism of some sort that i draw from scratch - let me know what dimensions i need to accomodate. And i have to present it to the class.