[OldMissileer]

I won't say for sure but I've heard, that you can take a model rocket engine, pry out the clay buffer and the top will become an ignition source...

Why use that much effort? Just buy the first stage engines used for a multi-stage rocket. There is no buffer at the top but a small hole to let the flame burn upward to ignite the second stage engine.

Instead of another engine/stage just fill the top of the rocket with black powder. It works very well.

[Big Red Badger]

First Stage of multi Stage Rocket,,,
Oh Boy!