For this exercise related to data visualisation I developed a small Grasshopper definition that reads a G-Code file and gives a very basic graphical output of the geometry contained in it. The singular part is that the file is read directly with no need to convert the data in a datasheet format, so no gHowl components are used here. The functionalty is still very limited and it gives some insight into the G-Code for engraving or cutting jobs but it is not useful for real 3D jobs yet. You can get a description PDF here. And a detail image here.