NavigationBaker based on https://learn.unity.com/tutorial/runtime-navmesh-generation#5c7f8528edbc2a002053b495 but more fun

NavigationBaker.cs

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

public class NavigationBaker : MonoBehaviour {

    public NavMeshSurface[] surfaces;
    public Transform[] objectsToRotate;

    // Use this for initialization
    void Update () 
    {

        for (int j = 0; j < objectsToRotate.Length; j++) 
        {
            objectsToRotate [j].localRotation = Quaternion.Euler (new Vector3 (0, 50*Time.deltaTime, 0) + objectsToRotate [j].localRotation.eulerAngles);
        }

        for (int i = 0; i < surfaces.Length; i++) 
        {
            surfaces [i].BuildNavMesh ();    
        }    
    }

}