there are a number of companies that make decal paper. two of them that i can think of off hand are micro mart and bare metal foil. with micro mart (maybe bare metal...not sure since i never used it but have seen it) you just make your own decals (i design mine on a cad system...but im sure u can use various pictures, ms paint, etc) then print them on your computers printer (if ya have one). you then have to "seal" the ink with a type of "dull coat" so the ink doesnt run. micro mart also sells that. you can find their site by a simple search by typing "micromart"! i would look into other companies as well...just do a search if ya want more than what i've given you. hope that helps ya!
btw, the only drawback to their decal film is it isnt very thin and its a pain to try to seal them sometimes. not to mention if you dont do it right then try using any type of solvents to adhere it better or form arouond weird shapes it tends to eat away the sealant and ruins the decal. however, it may or may not do the depending on if ya do it right...took me awhile to "get it" and im not sure about you but its too exspensive to "practice on"!!