Summary: In this paper we develop an improved three dimensional stochastic model for the lay-down of fibers on a moving conveyor belt in the production process of nonwoven materials. The model removes a drawback of a previous 3D model, that is the non-smoothness of the fiber paths. A similar result in the 2D case has been presented in [M. Herty et al., Kinet. Relat. Models 2, No. 3, 489–502 (2009; Zbl 1195.35102)]. The resulting equations are investigated for different limit situations and numerical simulations are presented.