In the gutter

Bufff, finally done. I found it interesting but extremely difficult and random, that's the reason I won't give five stars unless I am wrong and there is a reproducible way to win it. Thanks for sharing!

No there isn't. Depending on your skill and resulting speed of the balls, there is a 1-25% chance it will work (rough guess). If it doesn't work "don't feel gutted" and retry.

But I would never put something like this not as first step in a level.

Bufff,I sweated blood but I did it!!!

The only way I could consistently reproduce my efforts was to have B knock each ball down.

Spoiler

Chasing the final ball down the "sidewalk" not sending it down the gutter

Does that count?

@Lianne Malone See what you mean. Well yes that counts, it's clean and quite controllable.

I like it! I won on my second restart, yay!