Highlight specific edges of a shape I have a semi-cylinder and I'd like to highlight the arc on the front, made of lots of vertices and smoothed. How can I highlight this? Best would be some kind of coloured glow to represent the arc.
I tried using a wireframe modifier but it seems the wireframe requires an actual shape, not just a line of vertices.
I wasn't able to add a glow to just the vertices either.
You can select the vertices you want and duplicate them.  Right click to send them back to their original position.  Then press P and select Separate by selection.

Go back to object mode and select your new object.
If your selection has any faces, enter edit mode and delete only faces.

At this point you have a circle, or a loop, or maybe just a line of vertices.  You're now able to convert this to a curve from Object mode.

You can give this some bevel depth.

And then apply a shader.  For example, volumetric emission.