Organ

An organ can be built inside the Chapel of a player-owned house with a Construction level of 69. This requires 4 mahogany planks and 6 steel bars.

The organ can be interacted with using the 'Play' option, but, unlike the Windchimes and the Bells, the sound can only be heard with music option on. If you play the organ in your player-owned house, then leave, it would still be playing until finished.

Bells can be heard while playing the organ, despite no bells being present on the instrument. This is likely due to the presence of tuned percussions such as glockenspiels or carrilions on many real-life pipe organs, which while instruments in and of themselves, are often considered part of a single, larger instrument.