Unknown Glass Painting - Need Directions

My add when I was little made a Lord's Prayer on glass, This is how I think he did it however haven't been able to find directions on the internet to verify before doing it.

1. Paint glass black
2. With lettering in reverse trace on to the black paint
3. Scratch out the lettering with a razer blade
4. Spray paint with read paint over the black, this makes the letters read with the surrounding black.

I am wanting to try this with my older kids at youth group however wasn't exactly sure if I am correct. If anyone has an ideas, I am open to them or knows what this is called for an internet search. Thanks.