Model X Change allow you to collect almost 400 pornstar cards. Open a free pack every 8 hours to get a new random card, that you can keep in your collection or sell on the global market to other players. The virtual currency earned from the market can be used to buy more packs. The cards have different level of rarities, and each card has its holographic version, which is way more difficult to get due to its low drop rate.
You can also earn currency by answering quizzes where you have to recognize the pornstar given its picture.