Download of LuxRender 1.6 for Mac was available from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. This free Mac app is a product of LuxRender Team. Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe. The application lies within Design & Photo Tools, more precisely 3D Modeling.
From the developer:
LuxRender is a physically based and unbiased rendering engine. The program simulates the flow of light according to physical equations, thus producing realistic images of photographic quality. LuxRender comprises an interactive user interface and exporters for various 3D programs, including Blender, 3Ds Max and XSI. Additionally, a command line tool is available.
You may want to check out more software for Mac, such as LuxMark, which might be similar to LuxRender.
Simulation
3D Design