Convert Materials to 3D Shader

Select the Materials you want to convert then right click -> AllIn1 -> Convert materials to AllIn13DShader:

You'll then be prompted with a window like this one. You can decide if you want to override the Material or create a fresh new copy:

The Materials created or modified this way will try to port over all the properties they can, meaning that when moving from the Standard Shader to the 3D Shader most properties such as textures, metallic and smoothness values, ambient occlusion, normals etc will carry over.