McCartney said most of the Beatles' material has been released. He added the unfinished post-Beatle Lennon songs were too poor in audio quality to fix with the tools available before Harrison died or that Yoko would not agree to let them use them.
He said one Beatle cut remains unreleased and it is called Carnival of Light. It is similar to the electronic piece Revolution #9 that many think simulates an LSD trip.
Like #9, I suspect Carnival of Light features tape loops, backwards tapes, and tracks played on an early analog sampler called a Mellotron the use of which Paul pioneered. (This keyboard was famously used on the Elton John's song Daniel.)
McCartney said Harrison did not feel like the track merited release. But, I suspect for legal reasons the track will come out ten years after the Love album.
I once made a parody of Revolution #9. I suggest you try making something similar as I did learn a lot about editing, composition, textures, and audio manipulation.
In fact, I ended up manipulating myself. One piece of mine used heavily edited versions of other's compositions. Much later, I realized this piece was about my desire to perform fellatio. Not only was fellatio rare then, but I thought I just liked girls!