Analog Sandbox Modeling (ASM) is a physical modeling method used to illustrate the formation of geological features such as faults and folds in sedimentary basins that could host petroleum accumulation and storage systems. These basins are commonly deformed. This research aims to investigate the characteristics and distribution of geological structures formed in an extensional system above the basal detachment with a planar footwall. Homogeneous isotropic material (i.e., 50–40 mesh-sized quartz sand or 0.3–0.4 mm) was utilized, exhibiting linear properties with a Navier-Coulomb behavior curve and a friction angle (Ø) 31˚. Five trials were simulated, each trial initiated from 25% and ended with a 100% extension. Experiments 1–5 resulted in 14–15 faults at 100% extension, with an increasing number of faults observed at higher extension rates. Although synthetic normal faults are dominant, antithetic faults were consistently formed first. The faults were initially planar, and they became listric as extension continued. The relationship between fault dip angles and extension magnitude showed a trend where the synthetic normal faults experienced decreasing dip angles, while antithetic faults exhibited increasing dip angles, with extension. Insights from this sandbox modeling could be used as a consideration in understanding sedimentary basins with extensional tectonic regimes.