I took the standard "fill the 3x3 with numbers 1-9" and started messing around with the sums of different blocks. Sujiko puzzles add circles on the four main intersections and provide those as sums to help you figure out how to place 1-9 inside. I decided to see what would happen if you add other portions together instead.
The result was a rather pretty looking circuit board looking puzzle. Maybe I'll call it a Circuit Board Square?
I have to run some calculations to see if the permutations in the 3x3 can create the 9! unique answers.