https://sims4studio.com/thread/281/make-sims-clothing-recolor-transparency?page=1

This tutorial will show you how to make a top recolor that has transparent areas without EA's bump, shadow, and specular images showing up and ruining them.

The same technique can be used for pants, shorts, and skirt recolors. For a full body outfit you will need to download the male or female full body nude:

These will soon be included as a Sims 4 Studio Recolorable inside Sims 4 Studio but for now you need to download them and clone them as custom content. If you aren't sure how to do that there is a tutorial going over that in the tutorials section here.

What You Will Need:

Sims 4 Studio v. 2.0.0.6 or up

A 2D Editor - I used Paint.net but any 2D editor that can handle alpha images and .dds will do.

Create Your .package:

  1. Choose Create CAS Standalone.

  1. Filter by Gender - female, Age - adult, and Part Type - clothing top and pick the nude top.

  1. The model will show up with her default outfit on. Now that your .package is saved click Cancel.

Get images resources from the top you want to recolor:

  1. Choose Create CAS Standalone.

  1. Select an EA garment that you want to recolor. Again click the Next button. This time it doesn't matter what you name the .package because you are only doing this to get the texture