It’s hard to demo 3D printing (or design) in a workshop/classroom time scale. This little activity gives participants a personalized trinket that they design themselves and print. Printing time is 2-5 minutes and design time around 10 or 15 (the first time).
http://baldwisdom.com/simple-3d-printing-design-activity/
http://baldwisdom.com/simple-3d-printing-design-activity