This is the popular Bird/Cage Optical Illusion, featured in Tim Burtons movie "Sleepy Hollow". Johnny Depp would twirl it constantly to concentrate and amuse others. I always loved it (especially the cardinal), so i decided to make one just like it. Its actually not very hard, if its done right.
All you need is thick white paper, and some string. I used off-white heavy cardstock paper and brown yarn to give mine an aged look (like the movie). And i also drew on my pictures to look more authentic, but you dont have to.
Trace a circle on your paper & cut it out.
(if u dont have a stencil, try a jar lid. A bigger circle works best. ...My circle is 3 in. wide)
Find a picture of a birdcage & bird you like, and resize them on your computer to fit just inside the circle.
Take your birdcage picture, and make it as centered as possible and trace the outline onto the circle with pencil.
(I'm using a lightbox to help trace.)
Then color it in with a pen and ruler (i recommend a sharpie pen as it doesnt bleed).
<--Should look somethin like this.
~This Step Very Important!!~
Flip the circle over vertically (up to down). So now the blank side is facing up, and the top of the birdcage (on the back), is pointing down. (see picture)
*If you do this wrong, your bird could be upside down later! :O *
DRAWING THE BIRD:
Next find a light source to see through your paper (like a lightbox/sunny window/computer screen). You should see your upside down cage through it.
Now you need to draw/trace your bird on, so it fits ONLY inside the cage. Again trace it in pencil, then again with pens and colored pencils.
(Once your done drawing, your pictures should look upright on both sides when you flip it over vertically. Yay! Hard part over.)
Hole punch holes on each side of the circle in the middle. (for extra strength, i also modge-podged the holes so they cant rip)
Then attach the string. Cut 2 long pieces of yarn, Double it over, put the loop through the hole, then the loose ends through loop. Pull tight. (repeat)
Now your done! To use it, just hold the strings between your fingers and twirl it. Your flying bird should be trapped in a cage! Enjoy.
(To see the illusion in action, heres a link!!!)