Plastic crystals behave like true plastic metals under mechanical stress.
For example, closer to melting, plastic crystals show high ductility and/or malleability. Plastic crystals can flow through a hole under pressure. For example, aminoborane plastic crystals bend, twist and stretch with characteristic necking, under appropriate stress. These crystals can be literally shaped into any possible way, like copper or silver metals.
This way, they are very unique compared to other molecular crystals, which are generally brittle and fragile.