We demonstrate "Thermorph", a rapid prototyping system aims to print flat thermoplastic composites and trigger them to self-fold into 3D with arbitrary bending angles. An interactive web-based design platform is developed to allow users to input their desired 3D shape or design 2D pattern, and see the printer printing it out automatically. Thermorph employs a desktop FDM printer and low-cost printing filaments to make this 4D printing technique readily accessible for researchers, hobbyists, classrooms, museums and developing countries.