Tinkercad:
Tinkercad is a simple, free online 3D design and 3D printing app. Tinkercad is used by designers, hobbyists, teachers, and kids, to make toys, prototypes, home decor, Minecraft models, jewelry.
Makerbot printbot
MakerBot Print is free software that optimizes and streamlines the 3D printing process for any workflow. It allows you to discover, prepare, manage, and share 3D print
123d sculpt+
Our Galactic 3D Toolbox: we provide a selection of 10 astronomical objects, simply modeled to print well across a number of 3D printers.
Thingiverse
free social media library for 3d printing
MakerBot in the Classroom
NASA 3D models
Homunculus Nebula, asteroids (data-based)
Chandra 3D model of Cas
Chandra 3D model of Supernova 1987A
If possible, use USB sticks with each students name on it to keep track of individual CAD files.