A hand (yours will do at a pinch if you can't grab a kid's.)
A piece of paper
Two or more colours of felt pens (I used highlighters) and a black.
How to do it:
1. Place the hand on the paper, fingers spread out.
2. With the pencil, draw lightly around and up the wrist a little.
3. Starting at the wrist end of the paper, on the far left hand side corner, with one of the felt pens, draw a horizontal line up to the pencil contour, at which point you curve up until about the middle of the wrist, then curve down again (to about the same place where you would have been had you not curved at all) and continue the horizontal line. You don't have to worry about being a bit wobbly.
4. Start just above this line, and with the other colours, do the same thing.
5. Repeat until you have covered the whole paper. If you come to a finger just curve 'over' it and 'down' the other side. Draw horizontal lines where there is no finger.
6. With the same colour pens, go over the lines again just around where they cross the pencil. This will enhance the shadow effect. If you experiment, you can do it better than me. Pretend which side the 'light' is coming from and make other 'side' of the hand/finger darker (in shadow).
6. Stand back and admire your work! If you want to be fussy, you can rub out the pencil line.
It looks a bit like one of these, doesn't it?