This object is yet another remix of https://www.thingiverse.com/thing:4677926. I've previously used that design to create a mini-plate and 3 tile turning bridge. Again props to https://www.thingiverse.com/fredle1957/

This design is intended to keep four self returning transfers in alignment and prevent too much loss of kinetic energy as the marble passes down the line.  You can see the video below.

Supports are switched on and set to normal auto and snug.  This makes them a bit easier to remove and wastes less filament.