New Design Brief - Mechanisms

Our next design involves making a mechanical toy. Today we went on to an application on the computers to look at different designs that we can do. At the moment I am leaning towards doing the dog because I like how it looks and I can see how to make it. However it does look fairly simple compared to the others so I may add something to the design. I also like the pig and it seems more challenging than the dog. At the moment I don't know what I'll do because I want to be able to successfully make it but at the same time I don't want it to be too easy.