Occasionally on this blog you might here me mention the shops I sell through. Right now those are Zazzle and CafePress...though I sold through other similar venues in the past. These are print on demand services (or PODs). Unlike sites like Etsy or Ebay which only list the products sellers provide, print on demand services actually work in partnership with the artists to make those products. The artists provide the designs and the print on demand service creates digital mock-ups of how those designs will look on products, then when someone orders those products they print them and ship them to the customer. Like Etsy and Ebay most PODS provide their artists with their own shop, and also list their products collectively in a general marketplace where customers can browse all the designs artists offer there.
You can find out more about the PODS I currently sell through and have sold through in the past here.