If gear bits A and B are turned same directions, intercept a blue ball. Otherwise, intercept a red ball.
A very tricky task. I had fun solving it. Solver gives out a lot of solutions, but the parts are so cunningly arranged that most of the solutions cannot be implemented with such an arrangement. I am not sure that this task can be solved without solver. I wouldn’t be able to :(.
I tried quite hard, but I couldn’t get the final set of four possibilities. I agree with the previous comment and also think this might be almost impossible to do without a solver. Here is my best attempt (you’ll still need to place bits A+B): Tumble Together
Here is my mess of a design. Made by me, no solver needed. Feel free to improve it, I’m just happy I made anything that works.
I accidentally sent the wrong url, sorry. Just imagine a ton of gears.
Here is a working link with no gears! Also made by me.