styro foam cup printing - might make a good relief/substitute teaching piece as well (fairly unique) - but instead of paint, maybe use a cup and ink pad, colour in with markers or crayons, or pencils (whatever is on hand and best to use with that particular group)
20 Amazing Creations You Can Make With 3D Printing
3-D coffee cups. These are espresso coffee cups printed out of Glazed Ceramics. The printing process takes almost a full day, and the One Cup a Day project aims to design and create 30 unique cups in 30 days. You can purchase their creations from this website where prices range from $36 to $77.