This year I have used Blendspace to create project-based learning modules for my middle school. It's a great way to easily integrate multimedia into the learning experience and reach a diverse array of interests. Recently, my students have started the 3D printing one which has them consider the history, possibilities, and challenges faced with this new technology. As the culmination, they design an object and print it, after which they consider further iterations and how to make improvements.
Here's an example of a student who printed a stand for his phone so it can sit horizontally as he uses it for viewing purposes, monogrammed with his initials and all.
Total printing time was over 3 hours and the phone was not completely stable in the stand, so I asked the students to redesign their phone stand to reduce printing time AND have a more stable stand. So they did and here is their redesign.
Print time went down...
I have another student working on a third design that is yet to be printed and will share that when it is ready.