What you'll need:
-A log (I used cedar)
-A few bottles (I like the look of old soda bottles, but you can use just about any type of bottle for this project)
-An old solar garden light with a 5-6V solar panel in it.
-A few LEDs (one for each bottle)
-Bottle caps (one for each bottle)
-A battery holder (I salvaged this and my LEDs from an old flashlight)
-Rechargeable batteries (I used 3 AAAs)
-Drill and bits (You will need some specialty bits: a 1" Forstner bit, a 5/16" diamond glass drilling bit and a hole saw)
-Soldering iron and solder
-Hot glue gun
-Screwdriver(s) (to take apart your solar light)
Step 1: Take Your Solar Light Apart
You may need a screwdriver to actually take apart the top cover to get all of the circuitry out of it. Use caution when removing the solar panel itself from the top cover. Sometimes you need to stick a very small flathead screwdriver or blade in beside the panel and wiggle it a bit to free the panel in order to remove it. Be very careful if you do this, as the solar panel is fragile and can break fairly easily if you start trying to pry it too hard. You may also need to snip the wires going from the circuit board to the solar panel in order to separate them from the top cover.
In my experience, the majority of solar garden lights don't fail because of the solar panel. It's much more likely that the batteries are just dead. You may get lucky and have some batteries that you can reuse from the light, but you may have to get some replacements.
Step 2: Slice Up Your Log!
Get your saw out and cut your pieces. I chose to stagger mine, so all three are slightly different heights. I also chose to attach mine together. To do this, I placed one slice offset on top of another, traced the outside of it onto the other log and then used a jigsaw to cut it. I then used wood glue to glue the pieces together.
Then you'll need to cut a fourth piece for your panel to mount to. I chose to cut mine at a bit of an angle so my panel gets more sun, but I'm sure it would be fine if yours is just straight up.
If you have a power sander or even just a piece of sandpaper, you can sand the top surface of your cuts just to make them a bit smoother, but it's not necessary.
Step 3: Make a Recess for Your Bottles and Solar Panel
If you decide to do it, here's how...
Get your hole saw out (I can't remember the exact diameter of the one I used, but it's the size you use to cut a hole in a door for a knob) and just drill down about 1/4" or even less. Then use a grinding bit in your Dremel to grind out all of the wood from the centre of your hole saw outline. I did this for my solar panel as well. For the solar panel, I traced an outline of it on the log and then Used the Dremel to get everything out to recess it a tiny bit.
At this point, you can also go ahead and drill a hole down through the centre of your pieces (right through the area where your bottles will sit).
Step 4: Drill Out Your Battery Compartment
Now you can also drill/cut out a section in the bottom of one of your logs for the small circuit board to fit into as well (I just made my cutout right next to my battery compartment hole).
It's also a god idea to use your Dremel with a grinding bit and cut a channel out of the bottom of your logs to connect the wiring for all of the LEDs.
Step 5: Drill Holes In Your Bottles
Grab your drill and your diamond bit. Drill one hole in the bottom of each of your bottles. You do not need to apply much pressure at all with the diamond bit. Be patient and let the bit do the work. It may take a minute or so to get through the bottle. Remember, you're not drilling through wood or metal! Just make sure your hole is big enough to fit an LED in afterwards.
*Note: I would recommend drilling in a sink or in a tub with water. The diamond bits need a lot of water in order to lubricate them. If you don't use water, you'll burn out your bit in no time.
Step 6: Get Your Wiring in Order
Now just solder the positive and negative leads of from your LEDs to the negative and positive posts on your circuit board where the original LED was soldered in.
Solder your battery terminals onto your circuit board.
If your circuit has a switch somewhere, now is a good time to find a good place to mount that as well.
I put a layer of silicon around the bottom of my solar panel before I placed it onto the log to keep the weather out (same idea as with the bottom of the bottles). Feed your wire from the solar panel through the hole in your log also before siliconing it in place.
The way my panel was wired was the negative wire goes to the negative battery terminal and the positive wire goes to the circuit board. Just follow the way yours was originally hooked up and re-solder it.
Step 7: Finishing Touches
It's a good idea to seal up the wiring in the channel underneath the logs with some silicon now too just to keep the weather out.
Anything else you feel like adding is fine too haha.