Elapid, that pic is great
Anyway, I have found in the past Barbies burn quite soundly with a variety of pyrotechnic compositions inserted through the head
Experimentation is strictly limited to sister's barbies however.
It would be kinda hard to drill a straight port from the head through to the legs, and the motor would require a non-combustible liner to prevent the nitrous from acting like a cutting torch on the casing. The body might also heat fast enough to structurally fail during firing, and plug the nozzle throat
Funny if you could make it work though.