Color pencil on sketchbook.
I used to have a real nice handcuff, heavy and cold. It was bought in Japan. Somehow at that time, two girls going shopping cuffed together was a sign of dear friendship, and handcuffs were available in most accessory shops in Osaka.
I showed it to my boyfriend at that time, obviously not just for friendship. He never got the hint. I lost it later when I moved. Never really use it. What a waste.
