While waiting for my Shapeways part to arrive, I went ahead and printed one of the DIYSG-003-B. The -B revision simply opened up the hole diameter for the camera mounting screws so that I could use a brass threaded insert.
I fired up the makerbot Replicator 2 and printed one from some blue PLA.
Next using a soldering iron, I melted them in place.
Overall the part is more than string enough to hold 2 cameras. I would want to paint it before mounting it for long term UV protection. I never painted PLA before, but I imagine the Krylon paint for plastics should work fine.