FabLab ModelMaker
Aspex Software
FabLab ModelMaker is an easy 3D modeling software using simple geometric shapes and printing them as nets for making paper models. Alternatively the printed geometric nets can be processed by an inexpensive Silhouette fabricator (CraftRobo) if your school has one, which scores, perforates, and cuts the net to form fold lines and trim it which is then used is then used to build the model.
Using FabLab Model Maker in the classroom can make the STEM curriculum much more relevant to the students, getting them to think of solutions to problems which are important to them personally.