I recall the original master being larger than 6.5" and closer between 8" and 10" squared. There are pulls from the original mold out there in forum members hands so maybe they will chime in. I forget if its brass or magnesium etchings but the original master was a series of flat etched panels affixed to an inner box support then it was molded. There is a ton of detail in the panels that would be washed out if a licensed version was to be taken from a pull of an original for mass production.
I'm actually going to be selling mine soon to raise funds for my local comicon here. I believe mine was one of the DocBrown ones. It came pre-assembled in a raw resin casting (nice and heavy!). Beautifully assembled.
I did what I could with the images I had at the time in the painting, so it would have to get redone, but I definitely will be selling soon on the Junkyard or auction. I know it's not often this version comes around and is more desired than the smaller scaled replicas from Universal and such.