Binary Birthday Card (2015)

When my sister turned 32, I decided to make a special card for her.  Since we both enjoy math and technology, I couldn't pass up the opportunity to play on the fact that 32 is an exact power of two.  I thought of making a card that expresses 32 as a binary number by using six LEDs, one of which lights up when you open the card:

Here's a close-up picture of the mechanism:

The LED which lights up, thanks to a coin cell and a strip of copper tape.