This will show you how to make a poster than changes as you walk past it!

Step 1: The 'William Hartnell' Step

In the beginning, take a trip to 100,000 years BC and visit:

http://marquisdegeek.com/pub/html5/drwho50/

and select the two images you want to use, and click 'Show Lenticular Image'.

You should then print this page in the largest format you can.

Step 2: The 'Patrick Troughton' Step

Cut the main image from the page, but leave two ice (warrior) white tabs on either side. These tabs should be the same size, but it is not vital.

Step 3: The 'Jon Pertwee' Step

Score lightly along the dividing lines between each strip. I used the edge of a jewelers screwdriver, but an axos claw is also ideal ;)

Step 4: The 'Tom Baker' Step

Fold along each score line in alternating directions. Create a valley fold between the first edge and the tab, followed by a mountain fold, and so on.

It will ultimately become as crinkled as Meglos!

Step 5: The 'Peter Davidson' Step

Fold the whole thing into a concertina, so it looks kinda like the picture below. I do it by gripping the paper tightly together, as I fold. Be as accurate as you can. You'll see on the image below that there's a slight issue on the left.

Step 6: The 'Colin Baker' Step

Cut a piece of card the same height as the paper, and about 2/3 of its original width. This width will vary the angle of each image slice, and consequently the viewing angle necessary to see the image.

Place twin strips of double-sided tape along the top and bottom edge of the card.

Then run glue along the left and right hand sides, about the same width as the white tabs on your paper.

Step 7: The 'Sylvester McCoy' Step

Align the paper carefully onto the card, and place something (like a box of licorice alsorts) on top for a few minutes, to ensure the creases in the paper stick to the tape underneath.

Step 8: The 'Paul McGann' Step

You're ready! (And about time!) Stick it to the wall, with blu-tac for example, keeping about a 50cm free either side, so passers-by can get a good look at it from each angle.

Step 9: The 'Christopher Ecclestone' Step

Look at it from one angle...

Step 10: The 'David Tennant' Step

...and then the other and start gurning at how brilliant it is!

Step 11: The 'Matt Smith' Step

It's complete!

I like lenticules. Lenticules are cool!

There's a short video, expanding on the image, here:

http://www.youtube.com/watch?v=A1c4o9MtdIw