By Maker Mig
This video is created with Blender 2.79 and shows colored arrows following over different colored extruded structures. It is done with two different methods. Both solutions use particle emitters to emit the arrow object.
The top curve has Force Field physics enabled , Type set to Force, and a Shape setting of Curve. Strength is set to -50, Flow is set to 10.
The bottom curve has Force Field physics enabled with with a Type setting of Curve Guide, and default values.