WIll this work or what else should I do?

I need to make a rugby ball cake and I want it to be round. So I thought I would make two halves of a rugby ball with aluminum foil then stick them together with butter cream icing. Will this work or will the foil shapes not stay. How else can I do it? I only have �3 to spend on this and �1.50 I have to use to buy modeling icing.