For my son's Adventure Time birthday this year (you can click here to see the cake, cupcakes and figures I made) I appliqued him a t-shirt that he wore to school on his actual birthday.
Here is how I did it....
First draw out the figures and then trace them onto the iron interfacing (you will need to reverse the design if it matters which way it faces). Trace each piece that is a different color separately.
Iron on the pieces to the correct color, do not cut out the pieces yet.
After the pieces are ironed on then cut them out- this will ensure that the iron interfacing goes all the way to the edge.
I made a back piece to iron all the little pieces on to for Finn. This back liner also has the iron interfacing on the back so I can iron it onto the shirt after attaching all the pieces.
I didn't have to make a backing for Jake because his body is all one color.
Iron all the pieces together then iron the completed figures on to the shirt.
Now all that is left is to zig-zag stitch all around the figures.
I painted Finn's eyes and mouth with fabric paint.
And that's all....