i made this name stamp for the back of my pieces of work and cards an' things in around 5 minutes flat - to make something similar you'll need:
a very strong piece of cardboard for the backing (or i used a piece of polystyrene that came from underneath a 'pizza express' pizza you cook yourself)
a sheet of fun foam (the thin stuff you cut with scissors)
weatherproof wood glue (this is basically a very strong pva that doesn't mind getting wet, hence the name, i got mine from a local diy place, more expensive but well worth it)
to make the stamp: freehand cut your letters, slap a bit o' glue on the backing, place your letters backwards on to the glue, leave to dry and bob's yer bleedin' uncle, a custom name stamp. and if you use those posh ink pads with it, you can stamp onto fabric too. groovy!
(totally off the subject, have you noticed that the children in the book look like they're loitering around an elephant's bum? i wouldn't stand there too long chaps, you're likely to get covered in shite.)