Hey, it's really kind of you to ask first! Feel free to make a shirt out of the design, just please, don't sell it for money. You can download the full-sized picture using the Download link on the right-hand side of the page.
This is a great picture, did some messing around and your picture has taught me allot! I traced around the lines and ended up with a cartoonish look, but I still give you all the credit and hope you don't mind that I uploaded the picture, and will remove it at your request. Nice picture and thank's for inspiring me!!!