To create new magazines for your game, first make sure to download and install an original set of magazines, such as Fashion Magazines Set 1 (read instructions for the installation).
After that first step, copy the original set (ex FashionMagazinesSet1) into your sims4studio mods folder (typically C:\Documents\Sims 4 Studio\Mods).
1. Open sims4studio, check Standalone Recolor option under Object button, and click Object.
2. In the new window, check Custo