DrawBounds.cs

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

public class DrawBounds : MonoBehaviour {

    // Use this for initialization
    void Start () {
    
    }
    
    // Update is called once per frame
    void Update () {
    
    }

    public bool _bIsSelected = true;

    void OnDrawGizmos()
    {
        if (_bIsSelected)
            OnDrawGizmosSelected();
    }


    void OnDrawGizmosSelected()
    {
        Gizmos.color = Color.yellow;
        Gizmos.DrawSphere(transform.position, 0.1f);  //center sphere
        if (transform.GetComponent<Renderer> () != null)
            Gizmos.DrawWireCube (transform.GetComponent<Renderer> ().bounds.center, transform.GetComponent<Renderer> ().bounds.size);
        else {
            Bounds bounds = new Bounds ();
            bool boundsInitialized = false;
            Renderer[] renderers = GetComponentsInChildren<Renderer> ();
            foreach (Renderer r in renderers) {
                if (!boundsInitialized) {
                    bounds = r.bounds;
                    boundsInitialized = true;
                } else {
                    bounds.Encapsulate (r.bounds);
                }
            }

            Gizmos.DrawWireCube (bounds.center, bounds.size);
        }
    }
}