You wont be able to design mutations, just mutate a whole load of things and breed for whatever you like that comes up. But remember kids mutations arent all laser eyes and schnickity schnickity most lead to cancers and other painfull deaths. Also in most countries experimentation on vertebrates without proper licensing (in the UK you need at least 3 different licenses, training etc.) is illegal, esp when your doing weird genetic stuff, so you might want to stick with insects and plants.