Hot dip spin coating has been successfully applied to the fabrication of optical waveguides in fluoroaluminate glasses for applications in integrated optics. Fluid dynamics modelling offers an efficient means to study the importance of the main physical effects and gain a deeper understanding of the process fundamentals. This knowledge enables the selection of the best material properties and processing conditions for a given quality requirement. The POLYFLOW CFD package has been used to better understand the hot dip spin coating process and optimise waveguides for uniformity and thickness. This paper describes the extension of previous successful two-dimensional modelling of the process to capture three-dimensional film non-uniformities.