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.