Code Question: Hallways

I am trying to match our ceiling texture on one sheet of drywall that was replaced because there was a closet that we removed. It doesn't need to match exactly, but close would be great.

I'm hoping someone might know a technique that could help me replicate this.

There seems to be somewhat of a round starburst pattern that is repeated in places but it's not as evident everywhere. I don't know if this was done with a brush, sponge or some other technique. It does seems like it was slightly smoothed out after the mud was initially applied.

How thick should the mud be when I'm applying it for texturing the ceiling, or is there a special compound that I should use?

If I can't replicate the original technique, is there any way I could use a piece of ceiling with the same texture as a mold to recreate the pattern. I wouldn't know what to use as a release agent so the mud wouldn't pull down when I removed the mold.

Any suggestions would be great.

Thanks!