How to replace dimensions (Nether.. etc.) in Minecraft and keeps the main world the same

Easy way to replace dimensions in Minecraft, I used Nether this time as an example, but it can work on most of the dimensions in Minecraft even a mod.
The condition is to know which folder is the dimension it stored.

1. Windows Explorer
2. %appdata%
3. .Minecraft
4. saves
5. the world with the favourite dimension
6. copy the dimension file and paste it into the favourite world folder
7. it should be working right now

Minecraft,