Teaching the properties of geometric shapes in traditional ways does not help children to understand them, nor does it enable them to visualize them. It may need methods that correspond to the characteristics and tendencies of children and more interesting methods based on fun learning. Designing 3D geometric shapes with children through pop-up mechanisms can offer a solution to their difficulties. Therefore, the current research aims to verify the current geometric thinking skills of children and the development of their geometric thinking skills in terms of distinguishing between the names of 2D and 3D geometric shapes and the properties of 3D geometric shapes after presenting a program based on the pop-up design mechanisms. The researchers developed a program to teach children to distinguish between the names and properties of 3D geometric shapes based on the design mechanisms that emerge. It has been called 3D through pop-ups in kindergarten children (3D POP-UP in KC). The research sample consisted of 12 children of (5:6) age groups. The study adopted the qualitative approach; data were collected through semi-structured interviews, observation, video recordings of children's handiwork, and photos during application. The results indicated that the participating children have a limited understanding of geometric thinking skills regarding the nomenclature and properties of 2D and 3D geometric shapes according to the results of the pre-test. It was also found that it is possible to teach them some geometric thinking skills such as distinguishing 3D and D2 geometric shapes and knowing their properties through the proposed program (3D POP-UP in KC). This result was shown in the difference between the children's scores on the pre-and post-test.