The invention refers to a system for producing three-dimensional figures with different shapes, including irregular and/or asymmetric figures, as from flexible sheet materials, consisting in supplying a sheet piece having a major segment or body, as well as at least one tab created unitary to the body, at least one slot disposed in the body and at least one point of inflection, so that it bends or folds the sheet piece at the point of inflection and passes the tab through the slot, causing the desired effect of bulkiness, depression or different plane and providing volume to the sheet piece and therefore the creation of a three-dimensional figure. The system of the invention has several applications, such as in toys, promotional goods, decorative figures, educational material, etc.