Light blue t-shirt
Piece of cardboard (or wax paper/tin foil/etc)
Your favorite picture of Sackboy
fabric painting brush
Blue water soluble fabric marker
Wash and dry the t-shirt. Lay flat on the counter and insert a piece of cardboard inside (keeps the paint from leaking through to the back). Mix your paints half and half with the textile medium. (I re-use the little cups apple sauce comes in and the cups that hold the icing in the refrigerated cinnamon roll packages for mixing paints).
I drew the Sackboy and logo with the fabric marker free-hand, but years ago I used what I think was called "pressure fax" paper. (You took the picture and traced it onto the special paper with the maroon pencil and then laid the paper face down on the fabric and used a wooden spoon to rub the lines onto the shirt. The lines would last several days before fading). I don't know if they still sell it, but it worked great!
I painted the words green and the Sackboy dark brown. Once it was dry I went over him with a light brownish tan paint in a chevron design to mimic knitted fabric. The eyes and mouth are black and the tongue pinkish. After all that was dry I painted the white zipper and pull and put in the white highlights for the eyes and tongue. Then take a beige and make the stitches around the top of his head and around his shoulders.
Outline the whole thing with a black fine tip sharpie. Heat set with a warm iron from the underside. Wash in cold water, gentle cycle. Lay flat to dry.
He was so excited when it was done and wants to wear it the first day of school next week.