COS was a very easy terminal to draw; everything was at right or 45º angles and there were no curves.
Normally, I rotate the terminal while I’m working on it so the majority of parallel lines are either completely horizontal or vertical. Doing so allows me to draw large portions of the terminal by creating overlapping rectangles and then combining them with Inkscape’s union tool, which is much faster than drawing a polygon for many building silhouettes. When I’m done, I rotate it back to its natural orientation (north is up on all of my silhouettes). However, to make this drawing even easier, the terminal was already naturally oriented due north/south, so I had no need need to rotate it.
Paul Bogard created these terminal silhouette illustrations, and has made them available for use under a CC BY-SA 4.0 License.