The eMessage in a Bottle is an easy project for the beginner circuit enthusiast. It clearly came about from me wanting to put my voice in a bottle. Remember as a kid you tried yelling into a bottle, closing it quickly, and then opening it near your ear only to be disappointed with sounds of the ocean. No longer!

Step 1: Materials + Tools

Materials:

Glass bottle + cork from Michaels or the cellar. You'll want a bottle with at least a 2cm diameter opening. The wider the opening the easier the project.
Record a message greeting card from Amazon. I chose this greeting card for the size of the sound module.
Old pair of ear buds or small headphones. These actually sound nicer than the speaker that comes with the card.
3.5mm headphone jack. Best salvaged from an old device.
SPST normally closed momentary switch. I used an RDI Intrusion Switch salvaged from an old Dell computer but you can purchase these off Ebay.
11" by 8.5" cardstock paper. Cardstock, so it can handle a little wear and tear.
clear packaging tape from the post office
solid core wire
solder

Tools:

rotary tool
wire strippers
soldering iron
scissors

Step 2: Record Your Message

This step is best done first in case complications arise later that prevent it. Take your greeting card and record your message like you normally would. Maybe use one of the smart-ass messages below.

"Help! I'm trapped in a bottle."

"If you let me out, I'll grant you three wishes."

"I can hear the ocean from in here."

Step 3: Salvage the Sound Module

Carefully tear apart the greeting card and remove the sound module with all its components.

Step 4: Swap the Speaker

Desolder the speaker that came with the greeting card. Solder wires to the 3.5mm headphone jack and then solder this to the sound module. Pole orientation doesn't matter but you should solder both the left and right headphone wires together for mono audio.

Step 5: Swap the Play Button

Desolder the Play button that came with the greeting card. Be careful not to desolder the Record button. Cut the connector off the RDI intrusion switch and strip the ends. Tape the RDI intrusion switch button down so it doesn't repeatedly trigger the sound module. Solder the exposed ends to where the Play button was once attached. Pole orientation doesn't matter. Plug your headphones in and untape the RDI intrusion switch to test that your circuit still works.

Step 6: Thin the Sound Module

This step may not be necessary if your bottle opening is wide enough. Go ahead and try placing your sound module into the bottle. No, it doesn't fit? We'll make it fit. Don some safety glasses and prep the rotary tool for sanding. Sand the sides of the sound module where there aren't any connections or metal paths. Careful not to sand away any components...or your hand. You should be able to sand a good 2mm off both sides. Test your circuit again.

Step 7: Make the Scroll

I wanted the circuit to be hidden and what better way to hide it than with a scroll of paper. You'll want the scroll nested in the bottle, not rolling around. The neck of the bottle should hold the scroll in place. Depending on the height of your bottle make the necessary cut to your cardstock so that the longest side will not protrude from the bottle. If your bottle opening is really narrow, you may want to use only half a sheet of paper. If your bottle opening is extremely narrow, you may have to cut slots in the side of your scroll for the sound module to protrude. This is only necessary if, in the previous step, your sound module just barely fits in the bottle opening and a piece of cardstock would add too much width.

Taking all of this into consideration, proceed to roll up your cardstock. Place one end of your roll into the bottle opening and, while still holding the other end with one hand, tape the end snugly. Proceed to tape your end and the middle for good measure. You should be able to push the scoll inside the bottle and remove it with ease.

Step 8: Place the Circuit in the Scroll

How you arrange your components is important. Ideally, the record button and mic would be on the bottom, the headphones would be near the top, and the RDI intrusion switch would be on the very top. All that's necessary is that the RDI intrusion switch is on top. Begin by threading the headphone wiring through, leaving the headphones right below the RDI intrusion switch. Next is the mic and circuit board. The rest of the components should fall into place.

Step 9: Enjoy

Place the scroll with all of its contents in the bottle. Remove the tape on the RDI intrusion switch and cork it. The cork should depress the button and prevent the circuit from triggering. Uncork your bottle and enjoy. I do not recommend tossing your bottle into the sea. There's enough of those in there already. eMessage in a Bottle does, however, make a great gift!