Within human boundaries

No Nen ability can be "beyond human boundaries." What this means is that you can't have an ability that is limitless. For example, you can't materialize a sword that can cut through anything. However, if you can set very strict conditions on it - then you can materialize a sword that can cut through anything given that the conditions are met. For example, Kurapika was unable to materialize an unbreakable chain. However, he was able to materialize a chain that was unbreakable by any Phantom Troupe member. Shizuku is able to materialize a vacuum cleaner which can suck up any nonliving object not created by Nen.