Plug-in for building Spreadshirt.com like store

Hi everyone.

I currently have a couple of t-shirt printing stores up and running. However I have this idea of building a t-shirt printing store (based on Woocommerce of course) that I would like to function similar to how Spreadshirt.com. What it should do it should let customers create and sell their own designs. The printing and shipping will be done by me the designer receiving a fee for each of their designs sold. I came across few plug-ins that let you create and buy a design printed on t-shirt, hoodie, etc. However is there some plug-in or add-on that would let my customer create their own store inside my store?

Looking forward to your ideas.

Regards
Saul