Coaxial Helicopter: Getting Started

Hi everyone,

I’ve successfully built a quadcopter using Arducopter, the Cube, and a DJI FlameWheel kit. Now that I’m slightly dangerous, I’d like to build a coax helicopter. I’ve seen some neat coax copters online, but since I’m brand new to them, I’m wondering if there’s a straightforward kit or step-by-step understandable design out there. Can anyone suggest something with which I can get my feet wet and have half a chance of success?

Thanks in advance!