This is actually the Halo 4 Forerunner Mantle. I modeled it in Sketch up mainly for my own use, but feel free to download it for yours. I attempted to get it as close to the original as possible, I am kinda a noob at design applications. It's approximately 6 3/4" in diameter, and like 3/8" tall? It was assumed to be lol, although I do not recall. I was/am using it for a Helmet Stand as the bottom plate.
Please Love! :)
Constructed completely from scratch in Sketch Upward. Literally laid down a level circle, drew all the details on and then began the extruding/chamfering/etc. procedure. It likely took like 3 hours or so, bunch of boring work, particularly since I am a huge rookie with all the applications. I exported it out to netfabb and corrected the size and set issues for printing after it was done. Subsequently re-exported it in STL format for shapeways.com.