This is one of many 3D designs made by my 3rd grade students. Students worked in small groups and used the engineering design process to solve their client's problem.
This group's client was the school secretary who needed a door stop. The only constraint for the design was that she did not want to have to pick it up from the floor. The group designed a door stop that doesn't even touch the ground. Bonus points if you can spot the secretary in the photos.