I started a red bubble account to sell my work and designs ranging from graphic prints and illustrations to Cushion cover designs. within my red bubble I sell a wide range of products such as phone case's and notebooks to blankets and shower curtains. There isn't really a limit.
The way Redbubble works is by uploading your design and applying it into their products. this way you art responsible for the print costs and postage fees. However this means you only earn 20% of the profits, as a result to be earning a lot you need a lot of sales to support it.