Help. Line overlay

I’m developing an extension for making a visual grid so I can align my renders to the rules of thirds, etc.
I need help as I don’t know how to make a line that is not an actual line in the 3D model but only act as an overlay. I’m searching for information as to how the scale frame option in revit works because it uses the same principles but I can’t find information
Can someone help me please I would truly appreciate it

If you wish coding help, please move topic to one of the Developers subcategories.
(Ruby if you’ll use Ruby. The SDK category if you’ll use C.)

By the way, the extension you are dreaming of has recently been created. See: