My son is 21 and he's a pacer and talks to himself. A wonderful man told me once, "Mom, when it's right you'll know it and until then keep searching". Make a square with threads and tell him what it's for and that you'll make as many as he wants. He might even want to help pick the colors. He picks at his clothes because that's what's always avalible to him. This would be a substitute that's ok to pick at. It's about self modification and helping to make good choices. We're still working at it and will for a long time to come and it's ok because we're still making progress.