This one done quickly with hardly any adjustments using the new superdooper Zdepth from a brush stroke. Paint your path with a stroke and the depth information on the canvas is utilized to position your object in the Z-Depth during the Animation. Fine adjustments need to be made on a frame to frame basis as the Depth might have a little offset from the edge to the center of your object causing it to sink into the surface. But the hard work is easily done for you. Also you can see from this animation I need to work on rolling balls heheh, Since my main rotation is on the Z-Axis I need to rotate the object perpendicular to the surface for it to roll right. Then there is the problem of getting the right speed over the surface :) That is a little harder.