Hi guys, this is my first Instructable and I will show you how to build some efficient speakers with just a little of duct tape and copper wire. I hope you enjoy! (Forgive my bad english, I will try to be as clear as possible)

Step 1: Materials

For this instructable you will need:
- Insulated copper wire (as thin as possible, a little more than a human hair)
- A pair of earphones
- A powerful magnet

and obviously......

- THE DUCT TAAAAAAPE (I used some Masking tape but any kind of tape is fine. the important thing is to have a sticky surface on which to paste the coil)

Step 2: Tools

For this instructable you will just need:
- Scissors
- Lighter

Step 3: The Surface

First you need to build the surface on which to assemble the speaker. Cut five strips of adhesive tape (about 10-11 cm long) and stick them close to each other (IMPORTANT: THE STICKY PART MUST BE FACING UP).
Then cut off the irregular sides

Step 4: The Coil

To build the coil just follow the drawing. When you reach the last coil (the smallest), cuts a thin strip of tape and (always with the sticky side upwards) stick it as in the picture, allowing the end of the wire to pass over to the other coils. In the end leave 5-6 cm long terminal.

Step 5: The Cable

To connect the speaker to the signal source you will need a stereo cable. You can buy one at http://www.radioshack.com or You can obtain it from a pair of headphones, as I did.

Step 6: Cardboard Support

If you want you can build a small cardboard support, for aesthetic reasons

Step 7: NOW TRY IT! :D

To use the speaker need only connect it to a source of audio signal and push your magnet toward the center of the coil. More the magnet will be close and higher will be the volume! First I connected it to my phone, but to hear the sound I had to literally stick it in my ear (it was like to wear headphones). Then I connected it to a very old cassette player (which amplifier was much more powerful) and you can hear the result in the video (you can feel the speaker vibrate if you hold it in your hand).
WARNING: DON'T to use this speaker for a long time and DON'T connect it to amplifying equipment that might be damaged. (I plugged it to a very old cassette recorder, and I have nothing to lose if it breaks). DON't ruin expensive equipment!

I hope you enjoyed,
bye!