Use mesh from another mod

Hello hiroki3

You can either use the button : my project from the sims4studio welcome window, open the package containing the mesh you want to rework and then export it.
Or you can add the package to the Sims4studio mod folder located in ~/my documents/sims4studio/mods -- restart S4S if it was opened -- and then create a new package by cloning this CC package.

Of course in case you want to publish the result, you will need to check the TOS of the original creators, get his approval or simply keep it for yourself.