Fill the balloon with water . This image illustrates why you don't completely fill the balloon you should always leave some room in the neck of the balloon, then as the form dries the pressure has somewhere to go and your clay wont split.
The best DIY projects & DIY ideas and tutorials: sewing, paper craft, DIY. DIY Board Ideas 2017 / 2018 DIY - How to make heart shaped wall art out of driftwood or tree branches and twigs. Includes tips on branch selection and show