I don't know much about the subject except that I use sketchup a fair bit; I'd be surprised if you find any straightforward way to export skp files to something you can print. I think you'd have to start with something like solidworks or vcarve or autocad.
Good luck, I want to see what sort of projects (preassembled air engine?) your class prints out. And I'd be interested if sketchup does play well with 3d printers.