Detail asset from Unity Asset Store: https://assetstore.unity.com/packages/tools/particles-effects/uvpaint-skinned-mesh-decal-system-61022
But now you can download UVPaint FREE.
UVPaint creates decals and immediately bakes them in needed ShaderProperty texture on 3D objects. It allows you to draw a variety of accessories and details into the 3D model at runtimewithout losing performance and video memory. Very easy and intuitive code.
• Does not require Unity PRO! (Unity 5)
• Supports Android and IOS;
• Does not create additional meshes;
• More Options;
• Works with custom Shader;
• Decals support any alpha channels;
• Unlimited decals on every skinned mesh;
• The possibility for creating a wide range of necessary decals;
• Only bake texture based on unwraped UV (you can create tattoo, details, blood splatter, etc.);
• You can draw back to the original texture using the Eraser.
With UVPaint you can easily give freedom to your imagination!
• Improoved perfomance.
• Fixed shader errors on Android(Pink textures).
• Fixed shader errors on IOS(Pink textures).
• Added direct access to Renderer arrays.
• Added UV cooudinate settings for the atlas.
unityassetcollection.com – Get all paid Unity Asset for free