Thank you very much Bagginsbill.

This will give me plenty to mull over. Right off the bat, I didn't know I could do this:

And I can combine all these into truly bizarre combinations

clr = (abs(n1 - n2) + abs(n1 - n3)) / 2
outputs += ["F", Surface(clr)]

Many Thanks

DR

 

"That government is best which governs the least, because its people discipline themselves."
Thomas Jefferson