On November 2, 2004, U.S. Patent No. 6,812,392 issued to Marlon Brando — yes, THAT Marlon Brando — on a Drumhead Tensioning Device and Method:

This was actually the fourth patent Brando received on this improvement in tuning conga drums, following U.S. Patent Nos. 6,410,833, 6,441,286, and 6,667,432. While his invention made it easier to tune conga drums, it would make the drums more expensive, and unfortunately it didn’t have a chance to catch on before his death in 2004.