Extension to allow users to "custom design" shirts

I am creating a Opencart site for a client who would like to sell "custom shirts", sports jerseys, caps, etc (and sell them on the website). he would like to be able to allow the user to customize their own shirts (select designs, or upload a design, etc ).

I was wondering if anyone knew of any "Design Your Own" software or extension that will work with Opencart, or had any alternative suggestions?

Just looking for a direction. Thank you.