3D Design Challenge Medals for students

I teach at a K-8 school, and my 3D printers are a constant source of curiosity for the kids. We don’t have room for design training in the curriculum, but I have an agreement with the kids that if they design it, I will print it. I was looking for a way to encourage students to learn design, and recognize those who did. I came up with biweekly challenges, each of which has a corresponding medal. This also solved a problem with having kids not know what to build next!