We got a cheap 'surplus' weather balloon on ebay ($2) and wanted to test it out!
This first test we're just using air - so it doesn't get away!
The latex is pretty thin, but seems strong enough. Its light, too.
We easily blew it up to at least 3 feet. When we put helium in it, it should be able to pickup and lift off with the cellphone haning from it. We might need several balloons, though!
A little shameless advertising on the balloon - just so it can find its way home.
Here's some video of our trial - first try went well, but the second got too close to the pine trees! Oh no! Oh well!
We'll get some more and try again - stay tuned!