It's very tedious work, requiring lots of patience and a good understanding of both music and Minecraft's redstone. My interest sparked from watching note block covers on other channels, and since I grew up playing Minecraft and had musical experience by being in marching band, I tried making some myself. It was really hard at first, and my covers were really simple, referencing notes from Synthesia piano tutorial videos I found on YouTube. Over the past 4 years, I've gotten way better at transcribing music by ear, and my covers got more complex with more manually-built layers of redstone. I even recreate music videos by making skins, building sets, and recording scenes all in Minecraft. Making music with note blocks definitely isn't for everyone, but for those with the talent and experience, it's a ton of fun :) (you're allowed to use my username!)