Hello folks, quite some time ago I included some methods for marking square lines on structural tubes where the corner radi are too large to allow for a standard square or speed square to work very well or very accurately. I'm reintroducing some of these methods along with an additional one. The last example allows you to position your rule and allow for the end to be used to "drag" along the tube when that sort of layout line is required. I would appreciate any comments, suggestions, examples from others on their approaches to this sort of challenge. I've included a number of pictures here. Best regards, Allan