Yin-Yang Balls: Easy to find in SF Chinatown on the cheap. I got these for $5.

Hasselblad 503cx, Planar 80/2.8 C T* f2.8 1/2 sec. ISO100, Fujichrome Velvia 100f slide film, True macro at about 4" from subject, with 32mm macro extension tube, tripod and cable release. My first medium format macro shot. Actual size about 1.2 inches in diameter.