Waypoint gizmo and waypoint manager

DuplicationHelpers.cs

using UnityEngine;
using UnityEditor;

// @kurtdekker
// Make sure this is in an Editor folder!

public static class DuplicationHelpers
{
	// duplicates the current object and puts it back right after the original.
	[MenuItem( "Assets/Dupe Here FFS")]
	static void DupeSelectedItemHereFFS()
	{
		foreach( var item in Selection.gameObjects)
		{
			int siblingOrder = item.transform.GetSiblingIndex();

			var originalName = item.name;

			var copy = GameObject.Instantiate<GameObject>( item, item.transform.parent);

			// TODO: do anything clever you want with the name, such as suffix it with +1, etc.

			copy.name = originalName;

			copy.transform.SetSiblingIndex( siblingOrder + 1);
		}
	}
}

WaypointGizmo.cs

using UnityEngine;
using System.Collections;

// @kurtdekker - place this on the parent of a set of ordered waypoints

public class WaypointGizmo : MonoBehaviour
{
	[Tooltip( "Enable duplication of this path in reverse.")]
	public bool CloneToInversePath = true;

	void Start()
	{
		WaypointListManager.Instance ().AvailablePaths.Add (transform);

		if (CloneToInversePath)
		{
			GameObject clone = new GameObject ("CloneToInversePath:" + name);

			// parent as our peer, position where our endpoint is
			clone.transform.SetParent (transform.parent);
			clone.transform.position = transform.GetChild( transform.childCount - 1).position;
			clone.transform.rotation =
				Quaternion.Euler ( 0, 180, 0) * transform.GetChild( transform.childCount - 1).rotation;
			
			// copy the path in reverse order, spinning the transforms just in case
			for (int i = 0; i < transform.childCount; i++)
			{
				int j = (transform.childCount - 1) - i;
				GameObject child = new GameObject( "cloned waypoint #" + i);
				child.transform.SetParent( clone.transform);
				child.transform.position = transform.GetChild ( j).position;
				child.transform.rotation =
					Quaternion.Euler ( 0, 180, 0) * transform.GetChild ( j).rotation;
			}

			WaypointGizmo wg = clone.AddComponent<WaypointGizmo>();
			wg.CloneToInversePath = false;
		}
	}

	void OnDrawGizmos()
	{
		if (transform.childCount > 0)
		{
			Vector3 offset = Vector3.up * 1.0f;
			Vector3 last = Vector3.zero;
			for (int i = 0; i < transform.childCount; i++)
			{
				Vector3 curr = transform.GetChild(i).position;
				Gizmos.color = Color.yellow;
				Gizmos.DrawLine( curr, curr + offset * 2);
				if (i > 0)
				{
					Gizmos.color = Color.white;
					Gizmos.DrawLine ( last + offset, curr + offset);
					Gizmos.color = Color.black;
					Gizmos.DrawLine ( last, curr);
				}
				last = curr;
			}
		}
	}
}

WaypointListManager.cs

using UnityEngine;
using System.Collections;
using System.Collections.Generic;

// @kurtdekker - waypoint manager pseudo-singleton

public class WaypointListManager : MonoBehaviour
{
	// this is NOT a singleton... it is a scene singleton!
	public static WaypointListManager Instance()
	{
		WaypointListManager wlm = FindObjectOfType<WaypointListManager>();
		if (!wlm)
		{
			wlm = new GameObject( "WaypointListManager.Instance();").
				AddComponent<WaypointListManager>();
			wlm.AvailablePaths = new List<Transform>();
		}
		return wlm;
	}

	public List<Transform> AvailablePaths;

	public Transform FindRandom()
	{
		AvailablePaths.RemoveAll (x => !x);

		if (AvailablePaths.Count < 1)
		{
			Debug.Log ("WaypointListManager: no AvailablePaths!");
			return null;
		}
		return AvailablePaths[Random.Range (0, AvailablePaths.Count)];
	}

	int NextCursor = -1;

	public void Shuffle()
	{
		if (AvailablePaths.Count > 1)
		{
			for (int i = 0; i < AvailablePaths.Count; i++)
			{
				int j = Random.Range ( i, AvailablePaths.Count);
				if (i != j)
				{
					var t = AvailablePaths[i];
					AvailablePaths[i] = AvailablePaths[j];
					AvailablePaths[j] = t;
				}
			}
		}
	}

	public Transform FindNext()
	{
		if (NextCursor < 0 || NextCursor >= AvailablePaths.Count)
		{
			NextCursor = 0;
			Shuffle ();
		}
		Transform found = AvailablePaths [NextCursor];
		NextCursor++;
		return found;
	}
}

Added the DuplicationHelpers because it's so helpful when inserting waypoints in this system.