The Sims 4 Studio is a new tool for making your own custom content for The Sims 4. Using this tool you can make your own custom accessories and you can recolor to your heart's content.  Some of the features the tools has are:
You can create your own new accessory meshes for the game and the accessory can have multiple recolor swatches in the same .package.

You can pick the item you want to replace or recolor by choosing from a thumbnail list that filters by various categories or searches by keyword:
You can preview your new custom mesh or recolor texture in a dynamic 3D model viewer that expands to fit your computer screen:
You can create default replacement recolors and standalone recolors easily and add multiple recolor swatches per project/.package.

Cloned EA meshes are imported into Blender positioned on a model Sim making it easy to size and position your mesh.  If you prefer another editor Blender can serve as a convenient go-between for many other 3D editors such as Maya, Milkshape, and 3DS Max.  More functionality for using this tool in combination with other editors is coming soon.

The link to download is at the top of this post.