Question about painting helmet w/ design?

[CBRAWR]

I was thinking that since I got this new spray gun and I'll most likely have extra paint left over after I finish painting my frame that I could go ahead and do some sort of a logo on my helmet too.

I was thinking of getting this....



and putting "Turtle" under it... (that's my nickname)

I was just wondering what type of material I would need.....I see on TV all the time where they use a stencil and was wondering if its just like a normal vinyl decal they stick down then remove after the paint dries or is it something completely different?