While browsing the February 2002 (why do they put these things out so early) issue of Games Magazine, I came across a short article about "Tilt Mazes", which are basically paper-n-pencil versions of those old marble-maze games --your marble can't stop until you hit a wall.
Noticing that this sounds awfully familiar, I tried it, and it works perfectly as a Duck Tiles level, only without the soaps. Here are a couple to try. I think you'll find 'em quite challenging.
I was able to solve this one without any help
I had to consult the answer page to get this one.
Have fun, and don't be afraid to submit something like this. There's not a rule that requires you to use soaps and sponges!