Additive manufacturing of laser heat sinks enables the optimization of cooling channel geometries and the integration of various functions within a single component. Lightweight and cost-effective designs can be realized using the fused filament fabrication process. Due to this manufacturing process, only a limited selection of materials is available. An appropriate choice of filament is crucial, since the material properties have a direct influence on the resulting thermal and mechanical stress in the laser crystal. A multiphysical simulation model in combination with a parametric material model is set up to investigate the influence of the properties of the heat sink on the resulting thermal loads in the crystal.