i dont know were to get the sticker sheets, but you can print them off the computer, and cut them, then glue them on the inside with this graphics stuff...hard to explain, i saw a how to once. Someone help me out hear.
But then you can put any graphic you want on there!!
These might help.
[link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXDA88&P=ML]decal[/link]

Hey i think i found it...
[link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXCEB9&P=7]Decal Applier maker stuff thingy!![/link]