The SFF (Solid Free-form Fabrication) Symposium is the longest-established 3D printing conference, which is sponsored by the University of Texas and held in Austin every year. The natural-direction 3D printing technology consists of field-oriented design technology, field-based tool-path generation technology, and non-horizontal (natural-direction-followed) 3D printing technology, which are patented and under development, and a new type of object model called the field-oriented solid model is used. The poster explains the outline of these technologies and the field-oriented solid model.