After using Blender for a few years to model the lego parts for Mecabricks, I started to look into realistic renderings.
I coded exporters for 3 formats .stl, .obj and .dae that can be imported in Blender. To make the import process easier, I also made available a Blender file with a script to replace the basic materials by proper materials for Cycles.
Please have a look at this video tutorial that shows how to use the template.
Here is an example of a model rendered by a user that didn’t really use Blender before:
Latest revision of Blender file can be downloaded here.
A gallery of renderings is also available here.