How to Add a 3D decor?

To add an element that will not end with the garment's edge, you can add any detail to an area where you want decor. The size of the detail depends on how big the decor item you want.

 

After that, you need to hide all characteristics of the detail, or you can make all detail's part transparent.

Then you can add any decor to that area, and it will not be cut with the outline of a garment's edge.