Sketchup is fantastic software, but not really suitable for what I want.
Im having a play around with visio right now, its a little clunky but does everything I need, I have draw a box for my overall CP dimensions, put a nice bezier curve on the botton edge, positioning accurate spheres for trackball/spinner/stick and button placements.
I am going to take this to the printshop tomorrow, get it printed to size
Drill out and test fit everything, if Im happy then I will work on the photoshop art using this template to label the controls etc..