I thought I'd post this here for those who haven't seen it. It's an amazing insight into the creative mind of Jacob Collier. Even though he's using Logic, the same techniques could be applied to Reaper.
It's pretty mind-blowing to tell you the truth. 331 tracks (pretty small by his standards)
https://www.youtube.com/watch?v=oQ8xKanSYUg
Enjoy!