This is an extremely easy hack. We will disassemble a solar yard light and hack it into a styrofoam skull that will give off an eerie eye shine at night. Check out the next page for the list of materials.
Step 1: Gather Materials and Tools
You need the following materials:
Styrofoam Skull -------- About $5 (Walmart)
Solar Light ---------------- Less than $1 (Department stores mark these down cheap in the fall.)
LED -------------------------- Less than $1 (This is optional. You only need this if you want to change the color of the eye shine)
Single AA Holder -------- 99 cents (Radio Shack part #2700401)
You need the following tools:
Phillips Screw Driver
Hot Glue Gun
Desoldering Pump or Solder Wick
1/4" Drill Bit
7/8" Forstner Bit or Hole Saw
1 3/4" Forstner Bit or Hole Saw
Note: Try to purchase a solar light that is about 2 inches in diameter(see photo) to allow easier fabrication. Also try to find a solar light that has a AA battery. Some solar lights will have smaller batteries that are difficult to find battery holders for.
Step 2: Hack the Solar Light
Use a phillips screwdriver to take apart the solar light. Inside the solar light you will find a small pcb and a NiCd rechargable AA battery. Look at the pcb to see if it is silkscreened with connection identification. If it is not then take note of the battery and solar cell connections observing polarity and desolder these connections. If you decide to change the color of the LED then also desolder that from the pcb and solder the new LED directly to the PCB.
Use an exacto knife to carefully remove the hot glue that holds the solar cell to the light housing. The hot glue is inside the housing where the wires come through. Be careful not to damage the solar cell but it is ok to damage the wires. Once the solar cell is removed then desolder the connecting wires. I used eight inches of twisted wire that I recycled from the inside of a LAN cable and soldered these wires to the solar cell. Make sure you note which color wire corrisponds to negative and positive.
Step 3: Carve the Skull
The next step is to carve the skull. We will start on the bottom of the skull. In the approximate center(see photo) use the 1 3/4" forstner bit or hole saw to carve out a hole about one inch deep. You can use a drill with the bits, but I find that just using your hand to spin the bit easily cuts through the soft styrofoam.
Next, turn the skull around to the front. We will use the 7/8" forstner bit or hole saw to carve out the eyes on the skull. Carve the eye sockets into the hole that we carved into the bottom of the skull, essentially creating a tunnel in the skull.
Now we will flip the skull over to the top. Take the solar cell that we salvaged from the solar light and place it on top of the skull approximately above the tunnel that we created in the bottom of the skull. Use a pencil to trace around the solar cell(see photo). Once you have traced around the solar cell remove it and use an xacto knife to cut the outline you just traced. You don't want to cut down into the lower eye tunnel. Only take enough foam away so the solar cell will sit down flush with the top of the skull (see photos). Use the 1/4" drill bit to create a small hole between the eye tunnel and the solar cell hole. This small hole is used to run the wiring from the solar cell down to the pcb which we will glue to the bottom of the skull. Place the solar cell into the hole that we created on the top after running the solar cell wires down the wiring hole.
Step 4: Heat Up the Soldering Iron and the Hot Glue Gun
Now we will solder the solar cell and new battery holder back to the solar light pcb. Make sure to observe proper polarity as noted on the pcb silkscreen or from the notes you took during disassembly. Make sure the NiCd AA battery has a charge and test the circuit to make sure it functions properly before continuing.
Reusing the base of the original solar light, hot glue the battery holder to one side and the pcb to the other side (see photos). Now orient the plastic base into the bottom of the skull so the LED faces up into the eye tunnel and the battery holder is accessible from the bottom. Hot glue the plastic base to the skull making sure it is adequately secure.
Use the ground stake that came with the solar light and firmly press it into the bottom of the skull (see photo) and secure it with hot glue. Skip this step and your skulls will be blowing down the road with the first gust of wind.
Step 5: Scare Some Trick-or-treaters
Now your project is done. Strategically place the skulls in your yard and you have a creepy solar light for halloween. Try varying this idea by painting the skull with glow-in-the-dark paint and using ultraviolet LEDs for cool effects. The ideas are endless!!!