three.js/src/extras/SceneUtils.js

/**
 * @author alteredq / http://alteredqualia.com/
 */

THREE.SceneUtils = {

	createMultiMaterialObject: function ( geometry, materials ) {

		var group = new THREE.Object3D();

		for ( var i = 0, l = materials.length; i < l; i ++ ) {

			group.add( new THREE.Mesh( geometry, materials[ i ] ) );

		}

		return group;

	},

	detach : function ( child, parent, scene ) {

		child.applyMatrix( parent.matrixWorld );
		parent.remove( child );
		scene.add( child );

	},

	attach: function ( child, scene, parent ) {

		var matrixWorldInverse = new THREE.Matrix4();
		matrixWorldInverse.getInverse( parent.matrixWorld );
		child.applyMatrix( matrixWorldInverse );

		scene.remove( child );
		parent.add( child );

	}

};