I have not used this software nor do I get any monetary value from them.
Small Stella, Great Stella, and Stella4D are computer programs which let you create and view polyhedra on the screen, then print out the unfolded nets required to build your own models out of paper. Small Stella has a fixed list of built-in models and can print out nets for over 300 polyhedra. Great Stella is more advanced, with many more built-in models, and tools for creating literally trillions of new ones. Stella4D includes everything from Great Stella, but adds support for 4D polytopes too. 4D models can be projected into 3D, and you can see their 3D cross-sections and nets in real-time.