Now, this isn't about some get-rich-quick method here. If you want to get rich quick, forget about trying to do it on the internet. Sure, Facebook ads are all the craze, but without a serious understanding of the mechanics behind sales funnels and conversion optimizations, which only comes after years and years of in-the-trenches work in the internet marketing field, you're largely wasting your time trying to "get rich quick."
If you have a flair for designing cool images, don't bother about creating your own inventory. As long as your design can be printed on a product, you can pocket some money. You can upload designs on various Websites such as CafePress, and if somebody orders these designs, the company will print them and distribute the products. It could be designs for T-shirts, hats, bags, books, posters, calendars, greeting cards, etc. You will receive a commission for each sale. Other such sites include Lulu and Zazzle.