The very first machines were actually "tin cylinders" not wax. My late Uncle had one of the very first. Edison origianlly intended it as a dictating machine. There has also been much talk between biographers that Edison "stole" many ideas from his employees - they invented it working for him BUT he took the credit. I mention this as it could be a great idea in a seance - a disgruntled employee of Edison coming back from the grave.
PSIncerely Yours,
Paul Alberstat