Yes sure; but it is rare to have indirection for every layer of a nested collection (i.e. each collection will essentially be a pointer to some data, with a little bit of metadata (like length & capacity for a Vec), so having Box<Vec<T>> is a pointer to a pointer to the data: essentially pointless!).

In other words, one would write

   Vec<Vec<Vec<T>>>

That might be considered ugly, but it's not ugliness caused by the `~` change.