Last layer?

[KirbyRockz]

If you look in the background of the "Be A Fort Minor Producer" screen, you can see a piano. I'm not good with identifing instruments, but maybe this is the last layer released?

[Dr. Octagonapus]

The last layer is vocals. The rest of the instrumental parts are all there already.

[JJ]

vocals mate - it will either be the microphone or the lyrics sheet i'd imagine