Made good progress on the line drawer tool today.
Mostly this consisted of ripping out the relevant parts I needed from the asset I got, and deleting everything else. I also had to made it work slightly differently. Basically, I needed to apply to every object in the scene (at least the geometry), and not just the one that I have selected.
I now have it where I can raycast from my mouse cursor in the scene view, and place a box on whatever geometry is right beneath the cursor.
The red box is the geometry I’ve placed.
The black circle bullseye thing is my “paintbrush” that lets me know I’m in this mode.
I need to make red boxes align to grid, and then create a mesh based on the red box position and order.