Drawing A Second Curved Line Which Is 3 Cm Far From The First One

[OptimusPrime364]

Lets say I drew the black line.

Now I want do draw the red line.

As you see the distance between the black line and the red line is 3 cm.

How can I draw the red line?

[Monika Gause]

There are plugins that can do that: ToolShed and Astute Graphics.

In Illustrator you could align the stroke to one side of the path and then convert to a shape

https://youtu.be/6zwX8AWqYlQ 

[OptimusPrime364]

Are there plugins for Ipad version as well?

[Monika Gause]

There are no plugins for the iPad version.

Sorry I overlooked that part of your question. Basically what you can do, is duplicate your path, then apply a 6 mm stroke to it, outline that stroke and then cut away what you do not need and also keep that original stroke of course.