The bars of the Triple Splitter sort the marbles correctly, but I still need to:
Feeding into the Triple Splitter, the Outer Spiral will circumnavigate the entire track. Large and medium marbles will roll around the entire track in a clockwise motion (as seen from the top), and small marbles will feed into the triple splitter from the other direction, though I don’t know exactly how far around the track they will go.
One idea I just now had is to allow the small marbles to circumnavigate the track on an inner loop, going the opposite direction.
Though the stand-in Outer Spiral is a polygon of sorts, I plan to make the real spiral smoother somehow.
Next to the triple splitter, I have a very narrow space to allow the small marbles to go down to feed into the small marble resting area from the other direction off of the Little Wiggly Track.
(*) Though there are not currently any plans for an upper zig zag, I guess there might have to be one later in the construction.
Make a stand-in Outer Spiral. I originally tried to do large segments of the spiral with long bamboo sticks, but they split while being curved. I ended up using shorter bamboo skewers, which make it more of a polygon than a smooth spiral.
Make a triple splitter. The trickiest bit was getting the spacing correct. As of about August 2018, the spacing is correct.
Have the bearing fly in like a helicopter. This was done by suspending it from a broom handle mounted above the whole set.
Have the stage on a bearing. This allows me to easily reach the far side of the stage to pose the characters / glue stuff / etc while making the animation.