Does the glass have to be cut?

Q: My front door is original from when my row house was built back in the 1920's and has 3 long windows down the middle of the door.

In order to gain more privacy without replacing the door, I was thinking of painting the glass to look like stained glass with my own design but I wouldn't want to take the glass out cut it and then put it back in.

Is there something I can use to separate the areas of color without having to cut into the glass? Thank you for your time.

Catie G