単一のマテリアルを追加・削除する。

AddMaterial.cs

using UnityEngine;
using System.Collections;

public class AddMaterial : MonoBehaviour {

	[SerializeField]
	Material edge;

	void OnEnable()
	{
		var render = GetComponentInChildren<Renderer>();
		int length = render.materials.Length;
		var materials = render.materials;
		System.Array.Resize<Material>( ref materials, length + 1);
		materials[ length ] = edge;
		render.materials = materials;
	}

	void OnDisable()
	{
		var render = GetComponentInChildren<Renderer>();
		int length = render.materials.Length;
		var materials = render.materials;
		System.Array.Resize<Material>( ref materials, length - 1);
		render.materials = materials;
	}
}