These prototypes were developed by designer Andrew Allen https://twitter.com/asallen working with prototyping engineer Amit Pitaru https://twitter.com/pitaru

If you'd like to discuss our approach to color blending, I can be reached at https://twitter.com/cmchen

Just curious, why'd you take down the prototypes? I'm assuming the actual app doesn't share any of that source.

Because FastCompany is consciously trying to publish more in-depth technical articles, in the manner of "Old Wired". I've chatted with the author of this article off an on for a couple of months now and I'm pretty happy to see that these articles are starting to hit publication.