Starting in year 3.0 of Skull-A-Day Noah opened up the project to 2 co-editors: Citizen Agent and Justin "Tatman" Lovorn. For year 4.0 the guys brought in an additional editor: Abby AKA Azurafae.

Each of the 3 editors took on their own yearlong skull-making project, agreeing to make an original skull every week for 52 weeks...
Abby's Weekly Skulls
Citizen Agent's Weekly Skulls
Tatman's Weekly Skulls