I have never used it, but it could still be worth it. If you are getting huge downloads, some may be interested in buying prints. Deviant may be taking a high percentage, but it is still passive income. Income from stock you do not have to maintain or ship.
Otherwise, as far as passive income goes, you could set up a RedBubble or similar print on demand and post the link in the post's description. RedBubble and Society6 give you a higher percentage back off sales.