Measure length of "curve" (or similar) by drawing on mesh I know there are a million answers on here about measuring the length of a curve (like this one, which is pretty much what I want to do) but I feel like this situation is a tiny bit different.  I have a scene like this:

Which is the real top of a skull, imported in &quot;real&quot; units.  I'd love to measure the circumference of that hole in the skull and return the length in centimeters, preferably by drawing on it.  I was drawing a curve by eyeball and using the CurveTools addon to get the length, but as you can imagine, its often hard to tell if you're in a correct 3d Plane and actually touching the surface and I often had to manually adjust each point I drew.  What I would love to do is &quot;paint&quot; like so:

And then have Blender measure the length of that, I imagine by creating a curve where that selection is? I tried separating the mesh by selection and then converting that new chunk into a &quot;curve&quot; and that technically happened, but the new curve couldn't be measured by Curvetools, not sure why.
Blender 2.9 if it matters.
Nevermind, found my solution here:
How can I make curves &quot;stick&quot; to a model?
Instead of drawing a selection and then creating a curve from that, you can draw your curve and have it snap to the object as you're drawing.