Rosen

Rosen is a lightweight mod that aims to expand on the noteblock system by adding more instruments, while trying to keep the sound design on the same level as the vanilla Minecraft.

Currently Rosen adds 18 new carefully crafted instruments such as Saxophone, Organ, Sitar, Music Box, Timpani and more! Rosen also features a Quality of Life addition that allows to play already existing instruments with the other blocks of a similar type.

How to add custom instruments (1.21.1+ only):

In your datapack, add a new json file named after your instrument to data/rosen/noteblock_instrument/ that follows this format:

{
 "name": "<instrument_name>",
 "sound_event": "<sound>"
}

Next, add a new file data/<namespace>/tags/block/<instrument_name>_noteblocks.json for the respective block tag that defines blocks to be used for your instrument that follows regular tag format:

{
  "values": [
    "<block>",
    "<other_block>",
    "<another_block>",
    ...
  ]
}

Voilà!