Tools Tab > Material Database Editor 
>
Allows you to add custom materials to the user material database.
The material database editors do not modify the data in the material database delivered with TANK. The software saves any custom materials to a secondary database, named umat.bin for API material and ENumat_2.bin for EN material. TANK saves the secondary databases in the System folder.
To select custom materials in TANK input, you must merge the custom material file with the TANK material database using Merge Material 
.