Small scale oscillations were recently observed in prominences with high resolution Hinode/SOT and IRIS SJI in unprecedented detail and identified as fast magnetosonic waves. The high-resolution observations provide evidence of flows of cool material, fluid instabilities such as Kelvin-Helmholtz and Rayleigh-Taylor, and the spectroscopic information provides evidence of Doppler shifts, heating, and cooling of the prominence material. Recently nonlinear fast magnetosonic waves were observed with periods in the range of 5-11 minutes and wavelengths in the plane of the sky (POS) of ~ 2000 km and flows, and the flows in narrow threads with POS speed ∼16-46 km/s. The nonlinear fast magnetosonic waves and flows were modeled using 2.5D MHD (Ofman & Kucera 2020). Here, we extend the study of the nonlinear fast magnetosonic waves using more realistic 3D MHD model. The model includes the 3D structure of the density and the magnetic field as well as mode coupling and demonstrate the propagating density compressions associated with the nonlinear fast magnetosonic waves, as well as the guided modes in the pillar. The 3D MHD modeling improve understanding of the POS effects in limb prominence oscillations observations. The results of the modeling are useful for coronal seismology of the prominence structure.