I wanted to remove some parts from the Prusa iteration 2 Mendel lm8uu plates and I got rendering errors in most of the files. For example, when rendering the x-end-motor.stl in mendel-plate-1, I get the following errors:
ERROR: Illegal polygonal object - make sure all polygons are defined with the same winding order. Skipping affected object.
I found a workaround by using Meslab to remove the unwanted parts and resaving the STL files but it would be nice to make it work in Openscad also.