u/ironmaster_18

It is said that Ravan used his own body parts to construct a Veena, also known as the Rudra Veena, one of his arms became the instrument's neck, his head formed the resonating chamber and his veins became the strings. He played the Shiva Tandav Stotram on this Rudra Veena due to which Bhagwan Shiv was impressed and gave him many boons.

Though, it is not in the Valmiki Ramayana, but it may be used to demonstrate the levels of devotion shown by Ravan.