your mice are pretty and cute,they are pets and it's part of why you love them so much.The brokens in the picture Sarahy has posted are mine,to make yours like mine you would need to breed and cull/kill hundreds if not thousands.Best to enjoy the animals you have as the lovely pets they are unless you want to deal with the harsh reality of producing marked mice for exhibition.Alternatively you could keep a look out for pet/fun shows.Some agricultural shows in the summer months have them,my son used to enter his pets at these.The London and Southern Counties mouse and rat club might do pet classes.