Coffee machines using disposable K-Cups are everywhere now. That means there are a lot of used K-Cups in kitchen and office waste baskets. This Instructable is a listing of some uses for spent K-Cups that come to my mind. There are pages on the Internet listing a dozen or 25 uses for spent K-Cups. The few I checked were done by women and reflected mostly feminine interests. Still, there is some overlap between ideas I am suggesting and things someone else may have posted. But, I have some ideas they do not have.
- Used or spent K-Cups
- Tape or a hot glue gun
- Hot glue gun (see above)
Step 1: First Things First
Remove the coffee grounds from the K-Cup and seal the hole.
A thumb is sufficient for removing the plastic top. See the first photo. Use a finger to remove most of the coffee grounds. Various web sites suggest uses for old coffee grounds from beauty and skin care to making soap to fertilizer to odor removal. Here is one such site.
See the second photo. The coffee grounds actually rest in a cellulose mesh envelope. Pull it out and away from the plastic shell of the K-Cup. It separates very easily from the plastic shell.
See the third photo. If you will use the K-Cup for storing larger items, the hole is of no consequence. If you will use the K-Cup for dry things, a piece of cellophane tape on the bottom of the K-Cup shell is sufficient. If you will use the K-Cup shell for liquids, a seal made with hot glue works well. Squirt a drop of hot glue into the hole from both the inside and the outside of the K-Cup. A small drop from both sides makes a very flat seal that is still effective and extends beyond the edges of the hole. I did not remove the burr from the puncture, but left it.
Step 2: Liquid Measure
A properly sealed plastic K-Cup shell holds exactly 1/4 cup (2 ounces) of liquid. (My finger is lightly dipped in water. Nearby is a 1/4 cup kitchen measure.) This would be handy in a home shop or garage for measuring 2-cycle oil to mix with gasoline for a string trimmer, blower, garden tiller, lawnmower, or chainsaw, assuming all of these have a 2-cycle engine. If you are away from home with access to a kitchen, but no measuring cups, and suddenly would like to cook something, some tape would likely seal a spent K-Cup shell long enough and well enough to do the job. If you want to measure a messy liquid, like 2-cycle oil or something equally unpleasant to clean up, a spent K-Cup can become a disposable measure.
Step 3: Tiny Funnel
When those serving on an altar guild must fill the very small plastic individual glasses for observances of the Lord's Supper, it can be a challenge. The plastic glasses are smaller than the private communion chalice shown in the photo. My second finger seals the hole on the bottom of a smooth, not dimpled or indented, bottom K-Cup. In order to reduce or eliminate dribble, hold the K-Cup at almost a 45 degree angle. Also use the other hand to grasp and steady the top of the K-Cup. With practice, it is possible to eliminate dribble. To refill, slide the second finger over the hole to seal it. With the other hand, pour from a bottle or measuring cup to refill the K-Cup. Then grasp the top of the K-Cup with the other hand and tip the K-Cup to almost 45 degrees.
A K-Cup funnel could be used wherever it is difficult to get oil into a difficult spot for lubrication. Because oil is thick, a slightly larger hole might be needed in the bottom. The K-Cup could be discarded after use.
Step 4: Wires, Cables and So On
This spent K-Cup is managing the wires from my ear buds while not in use. I coiled the wires around my fingers, and they should remain relatively untangled until I need them again.
Step 5: Electrical and Electronic
As an experiment, I cut two strips of aluminum foil for a homemade capacitor. Because the K-Cups are conical in shape, the strips of foil had to be in the shape of an arc. I rolled the K-Cup on the foil and the top edge made a little crease in the foil that made it easier to know how to cut the proper arc in the foil. Then I wrapped a K-Cup with the foil strip and slipped another K-Cup over the foil to hold it in place. I did this again over the first two K-Cups to make a capacitor. My multi-meter has a capacitance scale. The reading on the meter did not settle on one number, but cycled up and down, then up again. Still, the reading was part of a nano-farad, which is very small. If this were to be more than a curious experiment, multiple K-Cup capacitors would need to be ganged together in parallel. Here is a chart that allows you to see what your reading would be in micro-farads.
In my experiment I used alligator clips to make connections to the aluminum foil. It would be possible to remove the insulation from about an inch of copper wire and insert it between the aluminum foil and K-Cup. It would not be perfect, but it could work fairly well.
I thought about using spent K-Cups as a form for winding a coil, but the conical shape would make it too easy for windings to slip off of the coil. It might be possible to begin at the narrower end of the cup and fasten the wire in place with tape. The wire would provide a shoulder for successive turns of wire. But, these coils would be unusual in that the diameter of the coil is not uniform, but increases along the length of the coil.
Step 6: Game Pieces
Plastic K-Cup shells come in more than one color. K-Cup shells could be used as the pieces for a game of checkers. A checker board could be made to fit the game pieces with squares from construction paper on a piece of corrugated cardboard. The shells stack very well for storage between uses.
Step 7: Support
Spent K-Cups can be used as supports for extra shelves. Before I retired, I had a number of printed handouts I wanted to keep ready for when I needed them. I did not have file drawer space for them, but I did have some unused shelf space. But, I needed to add extra levels of shelves for my various handout documents. The photo is only a sample of what could be done using K-Cups to separate shelving material and utilize space more efficiently for keeping various documents.
Step 8: Take Your Pills
See the first photo. The small drinking cup on the left is purchased. My wife buys them and we use them for taking pills. The drinking cup on the right is a spent K-Cup with a hot glue seal on the hole in the bottom. A person taking pills could use spent K-Cups for free rather than buying drinking cups.
See the second photo. Many people have pill cases for the pills they take each day. Some put out the pills they will take each day while traveling. Although not completely space efficient, spent K-Cups could be used. Use a clear cling wrap and a rubber band to put a top on the K-Cup. Use as many K-Cups as needed.
Step 9: Seed Starters
Peaches3113 did a nice Instructable on using spent K-Cups for starting seeds before transplanting them to the garden. Some other sites suggesting how to reuse K-Cups also mention containers for seed starting.
Step 10: Light Diffuser
A spent K-Cup could be placed over an LED or a small incandescent bulb to make a night light, or a number of them could be used over bulbs to create party lighting, wherever soft lighting is needed. An Instructable by sally0630 used K-Cups to make party lighting, but she also painted the K-Cups.
I tried holding a spent K-Cup over the flash on my digital camera to see if that would soften shadows and give a more pleasing result than direct flash. It really did not soften shadows in my test photos, but only reduced the amount of light reaching the subject.
Years ago I used an old Weston hand-held light meter when taking photos. It was for reflected light metering. I liked the idea of reading exposures by incident light. I fitted part of a white L'Eggs Hosiery plastic egg over the light cell on my meter. At the time I knew the adjustment factor for light lost passing through the white plastic. If someone were using a hand-held meter for measuring reflected light and wanted to meter for incident light, a K-Cup over the meter's cell could be used.
(For those who are puzzled and curious, the switch failed on my Maglite flashlight. I chose to use a switch from Radio Shack as a replacement. Later I learned I could have returned the light to the factory for repair, but I did not want to wait or pay shipping costs.)
Step 11: Need a Float?
Perhaps you need a float to shut off water flow when the water reaches a certain level, or a float for a fishing line, or several floats to suspend a line or a net on top of water.
See the first photo (also used in step 1). Seal the hole in the bottom of two K-Cups. Apply a small drop of hot glue inside and outside over the hole. If needed, a string or a cord could pass through the bottom holes in each K-Cup before sealing the holes. Then get sufficient hot glue into the holes around the string. Or, secure string around the outside of the K-Cups after joining them as shown in the third photo.
See the second photo. Apply a bead of hot glue around to top edge of one K-Cup. Be slow enough to be certain there is good coverage. Be fast enough that the glue does not solidify before you are finished.
See the third photo. Press the two K-Cups together and hold until the glue has solidified. Test for leaks. If necessary, run a bead of hot glue around the outside of the joint between the two cups.
Step 12: Organizing, Etc.
K-Cups can organize and separate small items, like paper clips in a desk drawer. They can be used to separate different types of parts when dismantling something like a clock or a digital camera. They could be used for different denominations of coin if your commute includes toll booths and you do not have an electronic pass, but need exact change.
Step 13: Pinwheel or Water Wheel or Anemometer
In the photo I mounted six K-Cups on pieces of 3/16 inch dowel rod fastened into a hub. The hub is on a shaft. The assembly rotates with the pressure of my breath blown at it. The shaft could be mounted to a handle for a child's pinwheel, although it is a little bulky and has enough friction in the hub and axle that it would not spin as freely as a thin plastic pinwheel one might buy. Still, the principle could be used to do some light task where a water wheel would be appropriate. For the sake of giving credit, nkrauel did an Instructable about an anemometer made with paper drink cups.
Perhaps what I have offered will inspire you to repurpose some spent K-Cups in your own way. Anyone who drinks coffee regularly will generate more spent K-Cups than it is possible to repurpose each day. Still, it is an interesting challenge to give K-Cups a second life, especially if it means you do not need to buy something you might otherwise purchase. Early in this Instructable I linked a web page where someone suggested 25 uses for spent K-Cups. Most of the authors of such pages are women and their ideas are more feminine. I have tried to offer a few ideas that a man can really appreciate, as well.