Close Packed Crystal Models

These models were designed for use in my science classroom. When teaching crystal structures I wanted a model that shows how layers of close-packed atoms can form different crystal structures depending on how the layers are stacked. I also added a model showing the difference between cubic and close-packed atoms.

I started with the laser cut acrylic layers (dxf file). The circle size is similar to a penny so you can stack individual pennies to show the two different possible locations for the next layer. These are nice to show to a large class using an overhead projector or a light box and document camera. However they are tricky to align as they do not have "dips" that force the next layer to sit in the right spot. The 3D printed spheres solve this problem. The dxf file also includes a cubic array (not close packed) so you can easily compare these two arrangements

The STL files A and B are mirror images of an array of half-spheres. Print one each A and B then glue together