Absolute Mesh Combiner is a Unity 3D Editor asset that optimizes your 3D models to reduce the draw calls of your scene. It is easy to use as you only have to drag and drop a script and press the Optimize button to process.

It does the following steps:
– Create unique materials
– Create a texture atlas and update texture UV
– Merge game objects geometry (meshes and sub meshes) of the hierarchy in a single object
– Decimate the final mesh
– Save created assets to your Assets folder (Prefab, mesh, materials and textures)

Download it from Unity Assets Store