When using a sandbox to simulate tectonic activities, it is essential to thoroughly understand scale effect and its consequence so as to ensure an adequate model with representative simulation results. This paper investigates the topography, faulting lineaments, and internal structures of different scales associated with the simulation of plate convergence using sandbox modeling, based on three major test series. In the first test series, plate convergence is performed using simple models with flat bases to investigate fundamental behavior and observe the scale effect. The scales of sandbox models are altered either by varying the thickness of sand or by applying centrifugal conditions. The models have a relative depth scale of 1 : 2 : 20 : 40. In the second test series, the scale effects of a sandbox modeling given more realistic conditions are studied, i.e., models with underlain basement highs based on the configuration of western Taiwan. In the third test series, the impact of rougher base friction, and the effects of compaction are investigated to identify possible factors related to scale effect. Based on the observed scale effect, the possible factors accounting for scale effects are also discussed in this paper.