Interesting Street art in Enmore

Saw this today in Phillip St, Enmore, which is just opposite the Enmore Theatre. It's across the road and down a bit from the now absent supposed 'Banksy' piece. See http://reface.abc.net.au/_Banksy-in-Enmore/photo/2916752/65830.html.

It seems to be some home-made metal hemispheres about the size of half eggshells painted different colours and nailed to a telegraph pole. I am intrigued by the work that has gone into it. They are all quite high up, so the artist would have needed a ladder to attach them (or stood on top of a car). They are very uniform in size and I can't work out if they are things that have another purpose or if they are all hand made in some sort of a mould or form.

Any clues?