For in and out, above, about, below,
'Tis nothing but a Magic Shadow-show,
Play'd in a Box whose Candle is the Sun,
Round which we Phantom Figures come and go.
From Edward Fitzgerald's Rubaiyat of Omar Khayyam
My first thought was this is a clever computer generated image. The previous comments suggesting blown glass are, however, probably correct. Either way, it's a seasonally appropriate eye pleaser.