The Export Materials to MaterialX tool allows the export of V-Ray materials to MaterialX file (.mtlx), which can be transferred to other host apps and used to be rendered with V-Ray. The exported .mtlx file contains custom V-Ray data and can be used only with V-Ray.

To load the exported .mtlx files, use the VRayMaterialX material. 

UI Path: V-Ray menu > Tools > Export Materials to MaterialX (Experimental)

Materials to Export – Select which materials to export to a .mtlx file. 

All – Exports all materials created in the scene. 
Selection – Exports only the pre-selected materials or the materials of the pre-selected objects. 

Output MaterialX File – Sets the directory of the exported .mtlx file. 

Export and Close – Exports the material(s) and closes the window. 

Export – Exports the material(s) to the set .mtlx file. 

Close – Closes the window.