I’m fairly new to blender, (learning off and on because of school), I can’t remember what tutorial I seen this in, but the operation was extruding an uneven surface to a specific depth and it was in real time (meaning as you move your mouse towards the constrained depth the vertices would stop at that depth respectfully due to their position in space and mouse movement).
In other words, extrude an uneven surface flat to a specific depth.
Hopefully this makes sense…
Thanks!
Kevin