K-Cup Flashlights

K-Cups are an easy way to make your morning coffee, but they generate a lot of trash! We challenged our students to find new purposes for used K-Cups. One of our favorites is the K-Cup flashlight. What a great way to create a useful device, learn the fundamentals of circuitry, and keep excess trash out of our landfills.

For this project you will need:

1. A box cutter or hobby knife
2. An awl (or other tool that can make a small hole in the plastic K-Cup)
3. A pair of scissors

To build your K-Cup Flashlight you will need the following materials:

1. A K-Cup that has been emptied and thoroughly cleaned out (remove all filters and linings)
2. A cardboard tube (paper towel or toilet paper)
3. Copper tape - Click for example
4. (1) CR-2032 3V Lithium Battery - Click for example
5. Aluminum Foil (if you can reuse an old piece that isn't covered in food, even better)
6. (1) 5mm White LED Bulb - Click for example
7. Masking tape

Using your awl, carefully punch a hole in the bottom center of the K-Cup. If you choose, you can use the existing hole made by the coffee maker but it will be off centered. Try to make your hole just slightly smaller than the 5mm diameter of the LED bulb so that it will fit snugly in place in the next step.

Carefully press your LED though the hole you made in step one. If it does not fit snugly, you may want to add a bit of glue to hold it in place. Make a mental note at this point: One diode (wire) is longer than the other. In a later step, the longer stem will go to the positive side of the battery and the shorter end will connect to the negative side.

To make your flashlight more reflective and a bit brighter, line your K-Cup with aluminum foil. Be sure to push the bulb through so that it is not covered.

Using your hobby knife, or with the help of a teacher, cut a small tab into the side of your cardboard tube as seen in the picture above. Next, add a strip of copper tape from the opening of the tube where you plan to put your K-Cup and bulb.

• Insert your battery under the tab you cut in the previous step. Be sure that the positive (+) side is facing up. The wire you added in the previous step will connect the positive side of the battery to the long stem of the LED bulb when you flashlight is complete and you press the tab.
• Tape your battery in place being careful not to cover the center of the battery where the copper tape will make contact. See the images above.

• Attach the copper tape from the previous steps to the long stem of the battery.
• This one is a little tricky. Connect your short stem to the back of the battery inside the tube. BE SURE NOT TO OVERLAP OR TOUCH THE TWO STRIPS OF COPPER TAPE TOGETHER! This will create a short and your flashlight will fail to work.

Carefully, and without breaking or damaging the copper tape, insert and attach the K-Cup into the cardboard tube. Use masking tape to secure it in place.

If everything goes right, you should be able to press the tab to the battery and complete your circuit and turn on your flashlight.

1. Troubleshoot. Is your light not working? Check your wiring. You can refer to the diagrams above for help.
2. Working with students? Challenge them to improve the design or create entirely other purposes for used K-Cups.
3. Decorate your flashlight. Use colored tape, construction paper, puffy paint, glitter glue...