Quiet Wave-Creating Machinery

I'm seeking a specialized piece of machinery to create waves in a waterbed mattress. The mechanism should ideally be a crank and slider, converting circular motion to an up-and-down motion, repeatedly pushing down on the mattress. It needs to run for up to 9 hours. Key Requirements: - Electric power source - Whisper-quiet operation (20-30 dB maximum) - Cord length of 270 inches with an in-line on-off switch - A combination of metal and plastic materials Ideal Skills and Experience: - Mechanical engineering expertise - Experience with quiet electric motors - Proficiency in designing with metal and plastic materials - Ability to create custom, reliable machinery Please provide a detailed proposal, including relevant experience and estimated timelines.