Plasma-based waveguides are currently employed for laser wakefield acceleration to extend the focal region of laser beams. A parabolic transverse plasma density profile, suitable for laser guiding, can be established in a dielectric capillary as a consequence of a discharge in gas. In this work, we report on a new ray tracing model, based on the Zemax software, able to simulate the envelope of a laser beam propagating through a plasma waveguide. The potentialities offered by Zemax in terms of geometries and materials and the possibility to create custom objects do allow the simulation of complex and various scenarios, as for example curved plasma waveguides.