I had something come into work, and the first thought in my head was " wow, that would make a good start for a PKE meter". It’s not screen perfect, but still a pretty good start.
It’s a shoe polisher, that makes it alright despite being inaccurate. 
Have you made any progress on it yet? I’m working off of what I think is a newer model of that same thing, so I’m really interested to see what you do.
Looks good from my house. Run with it my man.