You can buy heat transfer paper at your local office supply store and make your own custom printed t-shirts. A more updated method is to use a digital ink jet printer that can print highly detailed images and photos on fabric.
Have you tried screen printing?
It was a big thing in the 80's, we used to do tie dye in the same craft class.
Maybe do some tie dye with lighter colours as a base, then screen print over the top in darker colours. (once the tie dye has dried of course)
**Hi again ... check this link, it has all the instruction and what materials to use,
I really hope you try it and have fun with your friend.
If you happen to become a top fashion designer who screen prints ... remember me, I'd love some samples!!! LOL