Lightweight and superstrong plastic bottle chain. The versatility of plastic is amazing. With plastic production ever-increasing, there need to be more efforts put into reusing plastics than having thousands of tons stored in landfills around the world. In this project, I used discarded plastic bottles I was able to find at the beach and in trash cans. We then turn them into a lightweight ultra-strong plastic chain that can be used in various applications from pulling and holding heavy objects, securing valuables, making swings or lightweight safety chains, etc. Great for underwater use due to corrosion resistance and repairability is just a new chain link away. So let's get started.

Supplies

Plastic Bottles
Piece of wood
Lighter
Drill
Wrench
Two 1/4" Bolts
Scissors
Knife

Step 1: Bottles to Strips

We need to cut the bottles into thin strips. I have found between 4mm-6mm cuts to be ideal for making a chain. There are a few ways to strip the bottles down. I used a scissor as I got the most consistent cut without breakage using this method. I tried making 3 different cutters where you would pull the end of the strip across a blade however they would break ever so often and the thickness of the cut would vary widely. Without a way to make an automated cutter precisely, using a scissor is the best way to get mostly even cuts along the entire length of the bottle. The best bottles to use would be smooth 2 liter bottles but any bottle can be used.

Remove the labeling from the bottle.
Cut off the bottom of the bottle right above the feet.
Use a scissor to cut the bottle into strips between 4-6mm all the way to the neck of the bottle.

Step 2: Making Link Assembly Tool

For this link assembly tool, you will need a base which can be anything you can get 2 bolts into, I used a piece of wood I had laying around. Ensure your base is at least an inch thick as the links will apply a lot of pressure to them when contracted. Your bolts need to be long enough where you can make multiple links before needing to remove them which makes the entire process a lot quicker.

Mark out 2 areas on your base which will hold your bolts. The wider you make them the longer each link will be.
Drill both holes 3/4 of an inch deep into your base to ensure they don't pull together under pressure.
Thread your holes using the bolts down into the base.

Step 3: Making Links

Now we will be making the links. This process of making individual links and joining links is quite similar with only one difference that I will get into shortly. The more links you can fit on your link assembly the faster this will be as you will need to remove one of the bolts to free the links.

The start of your plastic strip should be in the middle of the 2 bolts.
Depending on how thick you cut your strips, you will need to make 2-5 loops around your bolts. My strips are 6mm wide so I used 2 loops. Pull tightly at the end of each loop to remove any slack.
Once you've made your loops, you will be looping the plastic strip over and under the loops you've just made. Pull tightly at the end of each loop to remove any slack in the strip.
Carry your over and under loop from one bolt to the other, covering all the plastic from the oval loops you made earlier.
Once at the end of the bolt, pull the plastic strip over and under the bend in the link to carry the strip to the other side.
Repeat the over and under loops on the other side of the link, covering the loops made a the start.
Once you have covered the second side of the link, fit the plastic strip between the loops you made at the beginning and pull tightly to hold it in place. Cut off any excess strip, leaving only 4mm on the link.
Using your lighter on low heat, slowly heat up the plastic. You will see it contracting, creating a tight bond between layers.
Repeat the above steps until you've made a few links. I did 3 links at a time.
Undo one of the bolts from the base and release the links.
Each link should take around 5-7 minutes to make.

Joining links is a similar process with just 2 differences.

In the first step when making a link, place a completed link on one side and a second on the opposite side. Pay close attention to which link is facing you and which is away from you if colors and patterns are important.
Once you have made your loops and have moved on to wrapping your strip over and under. Feed your strip through the link on both sides once you've reached halfway down the link with the over and under process, moving in from in front the wrap to behind it.

Step 4:

Once you've joined all your links you're done. Feel free to make it as long as you'd like, the weight won't be an issue. I made mine 4 and a half feet. If there's a need for it to be longer, simply add more links and if it fails, simply join it with a new and stronger link with more loops. All my efforts to test its limits so far have not been able to get me to that point as the metal clasps/hooks fail before the chain. It's a bit overbuilt for taking dogs on a walk but a great alternative to traditional leashes which my pup loves chewing through.

Hope you enjoyed this project, have a great one.