I know I shouldn't be necroing this shit, but I wrote a neat little package that wraps all of this. GitHub repo.
If you're using 2018.3.x you can add the following to your manifest.json file in Packages folder:
"com.popcron.gizmos": "https://github.com/popcron/gizmos.git"
After that's installed, you can just call Gizmos.Line(a, b) and so on, and it will draw your gizmos for both the editor and builds. Let me know what you guys think of this, I'd be happy to listen to suggestions and feedback on its usability.
I currently use these gizmos in all of my personal games, so that I could hit F3 while I'm playing my game to test out hitboxes and bounds and such stuff.