If anyone's read the book i'd like to know in Silence Of The Lambs, how does Hannibal get that pen top ? remember just before he is being transferred. He sees a pen and looks at it, but i have no idea how he would be able to get it.

Because he was strapped up in that thing, but you see later when he's in that cell that he's got it and he uses it on the cuffs to escape. So how the hell does he get it ?