I know this is ancient history, but there is every chance that Cathy B has guessed correctly in Reply #8. I cannot see the sig in the photo - too small and out of focus. However...
Julio Santos did make many paperweights (and other objects) full of bubbles. I don't have any such weights myself to show, but three such can be seen on the websites of other Australian collectors here
A Google search for images turns up several others, mostly from recent ebay listings.