How to fill balloon with sand
I've tried to follow your instructions but cannot get the sand to fill the balloon to the size of a tennis ball. Actually I wouldn't mind it being slightly bigger. Once the sand is in, the balloon doesn't expand - i.e. I thought the more sand I put it the balloon would allow this to occur and would increase (as you would when you blow it up). So please help, I can't seem to get the size I need.