Physical CAD is a new type of CAD that models materials in detail. They bend, cut and crack like real materials, while you are designing.
Active materials are most useful when making things, but people who make things don't spend their day on CAD, so they are usually not expert CAD users.
Physical CAD lets makers contribute their expertise by simulating realistic tools.
Something special emerges: when you design a shape using accurate tools and materials, you are also designing a manufacturing process that can be used to make it.