Edit chosen material in the inspector for custom editor.

Hi, I know this topic is old but I think I have a nice way to achieve this with shader selection. I use a MaterialEditor with the following methods: MaterialEditor.DrawHeader () and MaterialEditor.OnInspectorGUI ().

Example code:

 using UnityEditor;
 
 [CustomEditor(typeof(MyScript))]
 public class MyScriptEditor : Editor
 {
     private MyScript _myScript;
 
     // We need to use and to call an instnace of the default MaterialEditor
     private MaterialEditor _materialEditor; 
 
     void OnEnable ()
     {
         _myScript = (MyScript)target;
 
         if (_myScript.material != null) {
             // Create an instance of the default MaterialEditor
             _materialEditor = (MaterialEditor)CreateEditor (_myScript.material);
         }
     }
 
     public override void OnInspectorGUI ()
     {
         EditorGUI.BeginChangeCheck ();
 
         // Draw the material field of MyScript
         EditorGUILayout.PropertyField (serializedObject.FindProperty ("material"));
 
         if (EditorGUI.EndChangeCheck ()) {
             serializedObject.ApplyModifiedProperties (); 
 
             if (_materialEditor != null) {
                 // Free the memory used by the previous MaterialEditor
                 DestroyImmediate (_materialEditor);
             }
 
             if (_myScript.material != null) {
                 // Create a new instance of the default MaterialEditor
                 _materialEditor = (MaterialEditor)CreateEditor (_myScript.material);
 
             }
         }
 
 
         if (_materialEditor != null) {
             // Draw the material's foldout and the material shader field
             // Required to call _materialEditor.OnInspectorGUI ();
             _materialEditor.DrawHeader (); 
         
             //  We need to prevent the user to edit Unity default materials
             bool isDefaultMaterial = !AssetDatabase.GetAssetPath (_myScript.material).StartsWith ("Assets");
 
             using (new EditorGUI.DisabledGroupScope(isDefaultMaterial)) {
 
                 // Draw the material properties
                 // Works only if the foldout of _materialEditor.DrawHeader () is open
                 _materialEditor.OnInspectorGUI (); 
             }
         }
     }
 
     void OnDisable ()
     {
         if (_materialEditor != null) {
             // Free the memory used by default MaterialEditor
             DestroyImmediate (_materialEditor);
         }
     }
 }

With the new Unity 4 Editor.CreateEditor class you can in fact render a preview interface as well. Here is a simple demonstration:

 using UnityEngine;
 using UnityEditor;

 class MaterialEditorWindow : EditorWindow {
 
     [MenuItem("Window/Material Editor Test")]
     static void ShowWindow() {
         GetWindow<MaterialEditorWindow>("Material Editor Test");
     }
 
     Material mat;
     Editor matEditor;
 
     void OnGUI() {
         mat = EditorGUILayout.ObjectField(mat, typeof(Material)) as Material;
         if (mat != null) {
             if (matEditor == null)
                 matEditor = Editor.CreateEditor(mat);
 
             matEditor.OnPreviewGUI(GUILayoutUtility.GetRect(200, 300), EditorStyles.whiteLabel);
         }
     }
 
 }