True! They should have a photo of the variations. Let's beat up on Shapeways for that. Where's my Nerf bat? HAHAHA!
I think they did have a photo up showing the variations in the past of just the plain unfinished material. They need to repost it along with the variations in the new finishes if they want to be fair.
As to your question, beside those that are here in the general discussion forum that will see your question there is the
Post Production Techniques forum that you can post the question to. Also, the best place to ask online is the forum at
Finishing.com where the worlds top experts in finishing hang out.
As for my suggestion of using a stainless steel blackener, after I posted that I remembered that variability is related to how much bronze ends up on the surface, consequently, stainless steel blackener is not going to be of much help since the light color is coming from the excess bronze. What is needed then is a bronze blackener for which I have no knowledge of, but experts in the field will probably know of something that will work well.