How can the video do this?

wai703597 · October 29, 2014, 5:35am

I am a non-English speaker, so I only can read and write English.

I am a beginner of Blender and have seen a youtube about the Blender tutorial.
The link is : https://www.youtube.com/watch?v=L9kA5LDJMLM

I have a disgusting how the video can do this at 30:01 to 30:04 ?
The video has shown a pink line, but how can i do by myself ?

Thank you for all of you who want to help me.
Thank you very much!

Richard_Marklew · October 29, 2014, 12:48pm