I recommend waiting to print the model until I double check that it is the appropriate size.
I'm judging by eye, but when I suck both your model and one of the hex triangles my OpenSCAD program generates, they look to be the same size when overlapped. Meshmixer has a number of complaints about your hedron, though; I don't know how they'll affect printing, but its automated mesh repair is, as is normal, stupid about fixing them, and destroys detail. Most of them look like places where the face greeblies on the hedron doesn't go all the way to the base plane of the face, and I don't think they'll be a problem. Nicely done.
Last Edit: Nov 27, 2016 7:59:35 GMT -6 by srmalloy