UnityのEditor拡張で､複数のオブジェクトから一括でPrefabを生成するものを書きました

// Copyright (c) 2021 Hiroyuki Kako
// This software is released under the MIT License, see LICENSE.
#if UNITY_EDITOR
using System.Collections.Generic;
using UnityEditor;
using UnityEngine;

public class MultiPrefabGenerator : EditorWindow
{
    [MenuItem("KEditorExtensions/MultiPrefabGenerator")]
    private static void Open()
    {
        GetWindow<MultiPrefabGenerator>("Generate multi prefab.");
    }

    public List<GameObject> _targetObjectsInEditor;
    private static string _path;
    private static string _objectPrefix;
    private static string _objectName;
    private static bool _wannaCount;
    private static bool _wannaNaming;
    public void OnGUI()
    {
        using (new GUILayout.HorizontalScope())
        {
            _path = EditorGUILayout.TextField("Enter target path", _path);
        }

        using (new GUILayout.HorizontalScope())
        {
            _objectPrefix = EditorGUILayout.TextField("Enter prefix when needed", _objectPrefix);
        }

        using (new GUILayout.HorizontalScope())
        {
            _wannaCount = EditorGUILayout.Toggle("Use count", _wannaCount);
        }

        using (new GUILayout.HorizontalScope())
        {
            _wannaNaming = EditorGUILayout.Toggle("Use original name", _wannaNaming);
            if (_wannaNaming)
            {
                _objectName = EditorGUILayout.TextField("Enter name", _objectName);
            }
        }

        using (new GUILayout.HorizontalScope())
        {
            ScriptableObject target = this;
            SerializedObject so = new SerializedObject(target);
            SerializedProperty stringsProperty = so.FindProperty("_targetObjectsInEditor");
            EditorGUILayout.PropertyField(stringsProperty, true);
            so.ApplyModifiedProperties();
        }

        if (GUILayout.Button("GeneratePrefab"))
        {
            if (!_path.EndsWith("/"))
                _path += "/";
            foreach (GameObject target in _targetObjectsInEditor)
            {
                string prefab = _path + _objectPrefix + (_wannaNaming ? _objectName : target.name) + (_wannaCount ? _targetObjectsInEditor.IndexOf(target).ToString() : "") + ".prefab";
                var result = PrefabUtility.SaveAsPrefabAsset(target, prefab);
                var newObject = PrefabUtility.InstantiatePrefab(result, target.transform.parent) as GameObject;
                newObject.transform.SetSiblingIndex(target.transform.GetSiblingIndex());
                DestroyImmediate(target);
            }

            _targetObjectsInEditor.Clear();
        }
    }
}
#endif