Rulers were the most important part of engineering. Before we had cad software, we were drafting using t-squares and set squares. If you had that manual drafting course you will get what it was like and be thankful to AutoCAD. But on the other hand it was real art to draw that drawings by hand. If you are really good at you may draft as fast as you can do at CAD but the main disadvantage with hand drafting is that you can’t do the revisions easily as you do in cad.