English: This is a 3D-printed fuel grain used in development testing at Purdue University for a hybrid rocket motor that would fit inside of a suitcase. The suitcase would be a portable education demonstrator, used for demonstrating rocket combustion.

The motor used nitrous oxide as the oxidizer and pyrodex pellets for the igniter.

The fuel grain pictured here also functions as the combustion chamber. Typical rocket motors (not used for demonstrations) have a case around the fuel grain in order to contain the pressure from the combustion events, however in this case, the fuel grain acts as the pressure vessel. The combustion events can be seen throughout the entire motor, including the nozzle.