The next step in 3D printing is 3D bio printing. With one of the 3D bio printer models, you can print using any solution that will go into a syringe-- lotion, chocolate, henna, bacteria, etc.
Students could use a 3d design program such as Tinkercad (it's free!) to create designs. Creating their own henna designs or chocolate creations would be a great way to create interest in CAD drawings, 3-D printers, and other technology for students who might not think that technology is for them.
Chocolate is definitely a gateway drug to almost anything and since there are a lot of science applications with bio printing, it could be a way teach students these specific skills before getting into (seemingly) less interesting science printing.
And since there are more and more researchers and technology firms focusing on bio printing, it would be a great way to connect with experts who are on the cutting edge of what is happening in science and technology. For example, Autodesk has a bioprinting department (and http://bionano.autodesk.com/) with whom a class could connect to learn about they are working on (human organ 3D printing-- oh my!)