Make:

Step 2: Soldering components

Let's start soldering. I added the 3 transistors and the 2K2 resistor in on step. Make sure you insert the transistors according to the diagram or it will not work.

Step 3: Connecting the capacitors

You need to connect the (2) supplied capacitors together prior to soldering them. Make sure you connect them with the (+) and (-) ends together. The arrows on the capacitors, which happen to point to the negative lead, should be pointing from right to left when looking at the board.

Now you can solder the capacitors to the board. Don't clip the leads yet! You can cut the (+) lead, but the (-) lead will be soldered to the switch in step 5.

Step 4: More soldering

Next, attach the pre-tinned copper wires to the board too. You can see them at the top of this picture. I used the 3rd hand to hold them in place while soldering. The (2) 3cm wires go in the middle of the (2) 7cm wires.

Step 5: Adding the switch and (1) more resistor

Solder the switch to the (-) side of the capacitors and to the twisted pair of wires you made in step 3.

While you are soldering the capacitor to the switch, you can add the 12k resistor to the back of the board. Make sure to read the directions carefully and solder it in the right spot. One end goes to the (+) side of the capacitors and the other goes to a trace on the board. The included directions are very clear, so make sure to double-check this connection.

Step 6: Attaching the speaker

It can be a bit tricky to solder the speaker. I found using the 3rd hand to hold the speaker in place and bending the (2) 3cm wires was the easiest way to solder them together.

Step 7: Final assembly

Next, screw the switch into the cardboard template that you cut out in step 1. Then feed the (2) 7cm leads through the holes in the template. Finally, solder the solar panel to the copper tinned leads. Make sure you orient the solar panel as described in the instructions. The panel can be tricky to solder, make sure you use enough heat. One of my solder joints broke while I was soldering the other. I went back and reheated it, now it seems perfect.

Step 9: Putting it all into the tin

Finally, push the whole thing underneath the lip of the tin. The cardboard ring will hold it away from the bottom. You might want to use a small screwdriver to slip the cardboard under the lip. It can be a bit tricky, but the template is a perfect fit.

Step 8: Make some music

Going further
You can add more resistors, a potentiometer or a mute button. This circuit is really easy to hack. The included circuit diagram includes a line-out variation so you can hook it up to an amp. I plan on modding mine, but more on that another time!