A unity mesh renderer inspector to view and modify renderer's sorting layer and material's render queue.

MeshRendererInspector.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using UnityEditor;
using UnityEngine;

[CustomEditor(typeof(MeshRenderer), true)]
public class MeshRendererInspector : Editor
{
	public override void OnInspectorGUI()
	{
		base.OnInspectorGUI();
		OnGUISortingLayer();
	}

	private void OnGUISortingLayer()
	{
		GUILayout.Space(6);

		var rend = (MeshRenderer)target;

		GUILayout.BeginVertical("box");

		var layerNames = SortingLayer.layers.Select(x => x.name).ToList();
		EditorGUI.BeginChangeCheck();
		var selectedIndex = EditorGUILayout.Popup("SortingLayerName", layerNames.IndexOf(rend.sortingLayerName), layerNames.ToArray());
		if (EditorGUI.EndChangeCheck())
		{
			rend.sortingLayerName = SortingLayer.layers[selectedIndex].name;
			EditorUtility.SetDirty(rend.gameObject);
		}

		EditorGUI.BeginChangeCheck();
		var sortingOrder = EditorGUILayout.IntField("SortingOrder", rend.sortingOrder);
		if (EditorGUI.EndChangeCheck())
		{
			rend.sortingOrder = sortingOrder;
			EditorUtility.SetDirty(rend.gameObject);
		}

		var mats = rend.sharedMaterials;
		foreach (var mat in mats)
			DrawMaterialRenderQueue(mat);

		GUILayout.EndVertical();
	}

	private void DrawMaterialRenderQueue(Material mat)
	{
		GUILayout.BeginHorizontal();
		EditorGUILayout.ObjectField(mat, typeof(Material), false);
		EditorGUI.BeginChangeCheck();
		var val = EditorGUILayout.IntField("RenderQueue", mat.renderQueue);
		if (EditorGUI.EndChangeCheck())
		{
			mat.renderQueue = val;
			EditorUtility.SetDirty(mat);
		}
		GUILayout.EndHorizontal();
	}
}