Answer:
The Material Library can be extended. If you add a new material, you can use it for all available models.
Click the "Create New Material" button in the library (see the image).
The "New Material" dialog box appears. The parameters of the entry selected in the "Material to Select" list are preset. Now, adjust the values. Creating a new material is easier when you select a material with similar properties first.
The user-defined materials are saved in the Materials_User.dbd file. This can be found in the master data folder of RFEM (C:\ProgramData\Dlubal\RFEM 5.xx\General Data). You can save the file and transfer it to another computer, if necessary.