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Material files carry a MXM extension. By default, materials cannot be edited or changed in RealFlow. To do this you need the Maxwell Material Editor. This tool is only available with the Maxwell Render Suite, and not part of your RealFlow distribution.
The RealFlow's library can be extended with materials from the Maxwell Render Resources website. All you have to do is to register, and download your favourites from several thousands of free materials:
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