I have released many of my paintings on a variety of products, here is a tiny sample, click through to see the range.
I originally did this through Cafepress but have outgrown them, I still have some available through Zazzle and Fine Art America, but Redbubble is now my choice and will be my primary focus for future releases based on service and quality but in a competitive market the perceived ‘best’ fit option will change over time.