Even though it’s for a box, this works incredibly well. I like it. I’m checking a few things then I’ll upload a blueprint function library version. Great work 
This works when measuring from the center to a point outward and works very well. Exactly what I need and asked for haha.
Usage demo based on an improved version of the template I updated earlier, method Pezzott1 made is included as a blueprint function library, I changed a few parameter names. Demo is set up to test intersections for any plane transform by any rotation step over tick.
Thanks all for the input, this is great. 