When it snowed, you can easely make a Ice Marble Run on a sloped surface, you need only a empty bottle and a plant spray.
The instructions begins at 1:34 in the video.
Test the track regularly while making the track.
If a marble get stuck, check the track for pits or holes, fill them up with some snow, then repeat steps 3 and 4 (spraying and sliding with bottle). When the slope is too small, try searching a better location. Otherwise use larger marbles or balls.
If a marble fly off track, try make higher walls along the track with snow and the plant spray. Otherwise, use lighter or smaller marbles.
I'm sorry, this is my first instructable, i'm from the Netherlands and my english is not very good.