I am implementing the ascii decoder for an earlier exercise, STL binary decoder, 26Sept2012. The STL ascii file specification I am using is available on wiki. A few C# 6.0 feature enhancements have been added (null propagation, string interpolation, expression-bodied members). Files tested are available in the assets directory under the project solution. Next step would be to add color decoding, logging and test it more thoroughly with defective STL files. Decoder needs to be more flexible, currently normal needs to be in the first line.