I was practicing the op10 no1 for a competition, and also I wanted to improvise the harmony of a fantasy I composed, so I asked myself "why not practice those pieces at the same time", then I started to improvise over the op10 no1 mixing the harmony of the fantasy with the etude's harmony.
Product Information Chopin - Etude op.10 no.1(Lucas Passos improvisation) by Lucas Passos - Digital Sheet Music