I've got a simple square plane (Blender 2.83) that is 66 x 66 meters and that I created by first adding a plane, then setting its X and Y dimensions in the n menu ("Item" tab in Object Mode) and pressing Ctrl+s in the end to "(Apply) Scale", so it afterwards also displays the right "edge length" in Edit Mode.
Now I want to extrude the corners to add a small border and make the plane 70 x 70 meters.
If I press e+s+2, the plane grows to twice its original size. To grow it to roughly 70m, I have to calculate the percentage (
70 / (66/100) = about 106), then extrude with e+s+1.06, which is of course still a tiny bit off.
How do I extrude with the actual measurement I want to add, instead of the percentage, e.g.: make e+s+2 add a small border to turn a 10x10 plane into a 14x14 plane (hence, add 2 units on each side)? Is there another way to do this without using extrusion, while still easily and quickly creating new vertices on the outside?
Edit: You can find a screenshot what I want to do (but with units, not percentages) here. Please don't mind the glitchy look, I didn't clean up the double faces.