This is one colour combo i can never see enough of, it looks really smart on the females with the Black, light grey and white effect, and Homozygous Cuckoo males look incredibly bright. It also worked on Barred, but personally i like the effect on cuckoo. You need to start with a Light (Homozygous) Cuckoo Male x A Mottled Female. The offspring produced will be Dark (Hetrozygous) Cuckoo Split Mottled Males and Cuckoo Split Mottled Females. You need to breed that generation together, breeding Brothers to Sisters, Alternatively if you have the room have two unrelated breeding groups of Light Cuckoo x Mottled, and combining those offspring together. Dark (Hetrozygous) Cuckoo Split Mottled Males x Cuckoo Split Mottled Female. will give you multiple phenotype & genotype offspring, In Females; 6.25% Black 6.25% Cuckoo 6.25% Mottled 12.5% Cuckoo Split Mottled 12.5% Black Split Mottled 6.25% Mottled Cuckoo In Males; 6.25% Light Cuckoo 6.25% Dark Cuckoo 12.5% Light Cuckoo Split Mottled 12.5% Dark Cuckoo Split Mottled 6.25% Mottled Light Cuckoo 6.25% Mottled Dark Cuckoo. From those offspring you have a couple of interesting options, In the above example you have Dark (hetrozygous) Cuckoo Mottled Male x Cuckoo Mottled Female. These produce, In Females; 25% Mottled 25% Cuckoo Mottled In Males; 25% Dark Cuckoo Mottled 25% Light Cuckoo Mottled Or Breeding Light (Homozygous) Cuckoo Mottled Male to Cuckoo Mottled Female, Breeds True.