So i Created a custom subassembly from a standard wood Drawer. I changed the material to  .765 Black MCP.

When i Create a New Project and bring this subassembly into a new cabinet i get this error "The Material: .765 Black MCP 2S cannot be found for Left Drawer Side in #1.01 - 1 Drawer Base. Please change the part material or add material to project." & it does not draw/display.

My question is how do i add the material to the project? The only way i figured to get the sub assembly into the new project/product is to "import" spec group from the project that i created it in. I am not fully understanding this spec group thing, & feel like i am overthinking it. All of the microvellum videos I came across dealing with spec groups explain the interface and give no examples, such as "oh i made this custom sub assembly with a sheet material that I added to the library, now lets save it to the global so you can bring it into any project."

Any help would be appreciated.