Here, I challenged myself to use My Blocks to identify repeating parts of a song and separate them into procedures (custom blocks) that I could call to from the main program. I even put custom blocks inside of custom blocks. See inside to see what I did and play with the tempo and the instrument.
You can check out my video tutorial on My Blocks on the official Scratch YouTube channel (ScratchTeam; look for the "Scratch My Blocks" video series) and find a link to written resources related to this topic in the video description.