2D drawing

For both the above: As an example the faces I’m measuring between in the drawing below are convex curved in two directions in the 3D drawing. The 2D drawing doesn’t allow me to find a point, line or curve for measurement at locations such as these. I would like to arbitrarily choose the location on the (in this case) projected 2D curve, so I can make my measurement. Obviously the accuracy in finding the true max length is limited to my skill in this case, but at the moment there doesn’t appear to be another way to do it. As it’s for cast iron I’d settle for a freehand version, especially if I could annotate the text of the measurement with words like “approx” etc. (The 101 and 104mm measurements there were added by me for the foundry in another application)

This would almost be a health benefit in the case of a left handed person using the control/zoom function where the control key is only present on the left.

But for my right handed self using the Magic Mouse, being able to scroll zoom, left click pan or centre click orbit etc would be great, leaving my left hand free to dance around the keypad for other shortcuts.

Having said that, the iPad is the preferred way to go for this app…