Developed by Eilish Cowan, Clement Gonondo, Adrienne O’Connor, and Patrick Squires

The P.E.T. is a do-it-yourself ocean plastic monitoring device based on filtering plastics through a mesh bag containing textured balls constructed out of materials easily found in household settings. The technology is anchored in the water and rests floating on the surface near a shoreline where plastics are commonly found. Water enters the technology from all angles and are entangled in the balls. The P.E.T. is designed to be light and portable so it can be easily transported to, from, and around the water.

The P.E.T. can be made out of multiple  variations of household items found in kitchens or bathrooms, can be bought for inexpensive amounts at stores such as Walmart, the Dollar Store and Pipers, or filter items can be scavenged or created from natural materials. Filter items can be determined by users based on the type of local plastics they hope to catch and the materials they have on hand. The P.E.T. is also designed to work over time and requires little to no physical labour. Instead of trawling the technology, the waves of the ocean are used to mix and naturally filter plastics through the technology. The technology can be left by itself in open waters without consistent monitoring. Users can choose to deploy, check-in, and pick up their technology whenever they please.

A full technology report for the P.E.T. is here.

Building Instructions

these are suggestions, as many items will work. Be sure to choose items that will not contaminate your sample with it’s own plastic debris!

For the bag/sac: A mesh laundry bag, A net garbage cover, a fruit bag

For the balls: plastic dish scrubbies, steel wool scrubber, loofas, grasses, pantyhose, sponges

For the anchor: Pillowcases, Burlap, or a reusable bag, plus rope and rocks

Tools & other materials: A luggage tag, Elastics, Scissors, Small zip-ties, Large zip-ties

bagStep 1: Create the bag
Choose a material to act as your technology’s exterior. I.e. half of a laundry bag based on its size. The material should be made out of mesh or a fabric that will let plastics and water pass through. The original P.E.T.’s bag was constructed out of a laundry bag. The user should make sure the bag is big enough to contain 5 balls. (Baseballs can be used to compare/ estimate size). A recommended size is 60cm x 45cm.

ballStep 2: Make your balls
The balls have two layers two them. In the original design the outside layer is made out steel wool and the inside layer is an intact plastic scrubber. Users should pull apart their outside layer, in this case the steel wool, and wrap it around the base layer, which is in this case the plastic scrubby. Others materials that can be used include loofahs, pantyhose’s and sponges. Both layers acts as entanglement and filtration devices.

zippedStep 3: Secure your balls
It is important that your outside layer stay attached to the base layer. To do so one can use small zip ties to attach the two together. Puncture the tie through both layers then lock it to itself, making it secure. This is done to prevent the balls from unravelling and coming apart. Other materials that can be used instead of zip ties include elastics and bobby pins that can be manipulated into securing the layers together.

lastStep 4: Place the balls in the bag.
Once you have created your balls out of your selected materials, you can them put them into your already created bag and secure it at the top with an elastic, rope or zip ties. It is crucial that the top be completely secure so that the bag does not open and let the balls escape. In the original design both zip ties and ropes were used for security.

Step 5: Attach your rope.
Your rope should be about five to six feet long so that it can be properly tied and give your P.E.T. room to float on the surface. Tie one end of the rope to the top of your bag, intertwining it through the mesh so that it stays secure. Attach the other end of your rope to the handles of your sustainable and rough material bag i.e. a burlap bag or a reusable grocery bag. This bag will act as one of the three layers of your anchor. It is recommended that users tie their rope with a bowline note to ensure its secureness. See Diagram below.

bow line
in waterStep 6
: Complete your anchor
Place your sustainable bag, with the attached rope, into two pillowcases. This will act as extra support and protection. One end of the rope should then be inside the pillow case attached to the sustainable bag while the other is on the outside attached to your technology and mesh bag. Fill the pillowcases and sustainable bag with rocks then close it with larger zip ties or another rope.
It is recommended that this step be completed at your launch site where you will be leaving your P.E.T. based on the heaviness of the rocks.

Step 7: Mark your balls
Use a luggage tag to identify your technology before putting it into the water. Write down your information and state that it is an ocean plastics monitoring device. Attach this tag to the bag of balls, so that it can be seen when floating. We recommend putting the P.E.T. is relatively gentle water close to the shore where tides will not make it so the bag is sometimes underwater and sometimes above water, as this will dislodge accumulated plastics.

plasticsStep 8: Recover P.E.T. and open balls
Plastics will be entangled in both the mesh bag and the balls, so remove the P.E.T. carefully from it’s location and place it in a bag. Recover any plastics you see immediately before transport so they will not be lost. Then, either in the field or in the lab, cut open the balls to see what they have caught. These are your samples!


A full technology report for the P.E.T. is here.

Creative Commons License
The Plastic Entanglement Trap (P.E.T.) by Eilish Cowan, Clement Gonondo, Adrienne O’Connor, Patrick Squires is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.