Two main processes are involved:
- Soap is blended, mixed and melted.
- Soap is pushed trough a moving hot nozzle.
The first person to talk about soap 3D printing technology has been Emanuele Mulas.
Here an article about the Soap01, considered to be the first personal 3D printer able to print in soap: http://3dprint.com/86207/soap01-soap-3d-printer/.