CELLPRENEUR: The Millionaire Prisoner’s Guidebook REVISED Edition. They say you can’t start a business while in prison legally and not violate your prison’s rules. Now, with Cellpreneur, a complete guidebook, it is possible to do just that and a whole lot more! Josh Kruger, life-term prisoner and self-made Cellpreneur, started a publishing business from a maximum-security prison cell. Author of The Millionaire Prisoner and Pen Pal Success, he shows you how you can do it too!