In the early 90s I had a book that was basically a large picture book within which lay clues realting to a mythical beast. The clues led you to assemble several odd bits of paper to form a tribal mask which when laid over the top of a certain page revealled the name of the famous monster in a gap (the mouth I think) of the mask. I think it was one of aseries of similar books - pretty sure there was a sci-fi one too.
Can any bookworm help me with the title because I'd love to share it with a new generation of reluctant boy readers.
Many thanks in advance!