I followed this tutorial:
But I printed two butterflies instead of drawing them to make them look realistic, plus I used VERY THICK cardstock and glued the printed wings on both sides.
Suggestion: use a VERY STRONG rubber bands or it will broke after a few spin.
ps: all credits goes to the inventor, not me. Only the photos you can see here are mine.
PPS: TRY AND CLOSE IT INTO A BOOK, THEN GIVE IT TO SOMEONE TO OPEN :P
In the future I will make a Steampunk one..