I found a certain technique that seems to work pretty well.

Set up green dots at every other position, and start building this "light" fence far away from the cat so it will not have time to approach the fence and force you to start building a solid fence to soon. When the cat finally approaches your "every second dot" fence it is very easy for you to close the gaps as the cat approaches. You can then control the movements of the cat instead of the cat forcing your moves.