Very nice! If I think back to the methods I had I had to laugh, as I saw, that it's so simple. Is it working with more than 100 cables in one line?

Try to use double values for the actors Location. Therefore you c an Import the smooth mover class in greenfoot and making it the superclass of all other ones. The driving would be much smoother.

I didn't used binary trees here, but I programmed a simple version of them last year in school with BlueJ. I can send you the class if you want (when I can find it). I can send you the code of some classes like the gates, too. It would be the best if you open a discussion like "Binary trees and Combinatorial curcuits", so that more users will help and code is better to see. I could explain you, how connecting the gates and all the stuff here works.

Yes that was my biggest problem. I tried to give ID's to the cables, but It it hasn't worked. I had some other methods. For example I tried to save them, in an array. I worked quite long on this, but with sh** solutions. :( You can download the sourcecode if you want. Maybe you can fix that. Later on in other scenarios I only used one big cable to ignore this. Therefore I wrote a method, that places it from one point to another. Watch here: http://www.greenfoot.org/scenarios/9271 If you fix that problem and if you upload your scenario, please tell me.