This idea came to us through a math video on youtube. My husband loves math videos and is constantly watching them in his free time, and it finally paid off. The video was about intersection solids. These shapes shapes are created with a boolean interesection and result in some really interesting shapes like a "Cork Plug"(intersection of a square, a triangle, and a circle) Essentially, multiple shapes overalap, and the boolean intersection is the shape that is shared.

We ended up using the Boolean function in CAD to find the overlapping cross section between a cylinder, cross, and pentagon.

We created a face that had a cicule, cross, and pentagon hole. The intersection solid we created could fit through each hole if it was rotated correctly. However, block would only fit through if the correct side was showing, so cross side could not fit through the circular hole.