These pieces were printed on a Makerbot Replicator 2 3D printer, by artist Cosmo Wenman, who printed them in several pieces and then assembled them. MakerBot is justifiably proud of these extraordinary achievements, which have really pushed the limits on 3D printing using low-cost, home-model printers. Here's some of Wenman's description of his thoughts behind Head of a Horse of Selene (a replica of a piece in the British Museum), on Thingiverse:
I find David Hockney's theories on the precocious use of lenses in Renaissance art very compelling. But living with this damned horse on my screen, and then in my house, for the last two months, it's hard to imagine how the original could have been designed two millenia ago without photography, let alone lenses. Its expression is so exacting, just an instant in time, I can't see how it could be modeled by eye from a live horse, or even a dead one. Maybe a contour gauge on a carcass with rigor mortis, but I don't see that either, not with this expressiveness and movement.
I imagine a Greek guy walking around 2,000 years ago with a camera obscura with some kind of light sensitive papyrus inside, trying to raise funds to get his light enscribing machine into mass production. Alas, there was no Kickstarter back then.
Or, maybe the artist and horse in bright sunlight, the artist covering his eyes. The horse's handler startles it into motion, and the artist opens his eyes for an instant, closes them again, then draws quickly with his eyes shut while the image fades in his retinas – the lens, film, and darkroom being his eyes… I dunno – either that or weeks of careful study, scores of sketches of impressions of a horse in motion, composited into this exacting model. But that doesn't sound like as much fun.