Introduction: Sandwich Toaster Plastic Recycling

About: Maker with an obsession for the 8-bit!

Reusing household plastic waste to make things using a panini press including a lamp shade, Christmas decorations, and a heart mobile.

In this 'ible I'll show a way to process some of your household waste using some pretty basic things to turn them into pretty or useful stuff. I'd love to see someone else's take on this project so please share if you give it a go and comment with any tips & tricks & advice you pick up along the way.

Step 1: Kit List

At the heart of this project is the sandwich press. Features that you should look out for are flat plates, and a variable temperature. If you're careful there's no reason you can't keep using it for your lunch, but I pretty much ruined mine over the course of the project so buy second hand if you can.

Stuff I used includes -

  • Flat plate sandwich Press (second hand from Ebay for around £30)
  • Grease proof paper (£1ish)
  • A brick
  • Stanley knife
  • Metal cookie cutters
  • A small amount of wood
  • Scissors
  • Jump rings (for jewelry making)
  • Pliers
  • Bradawl (or something "pokey")
  • A clamp
  • Drill with 2mm bit

Step 2: Lets Talk About Plastic

Not many people know this, but a lot of the plastic you lovingly sort into recycling boxes doesn't actually get recycled! And even then it becomes part of a global system that burns a lot of diesel transporting it and running processing plants etc. It's all terribly inefficient really, so every ounce that we can reuse helps.

Plastics tend to fit into seven categories. Each has unique properties and different melting points. The two we are going to focus on are HDPE (high density polyethylene) and PP (polypropylene). These are two of the most common waste plastics and have similar and relatively low melting/softening points. I mostly met them in the form of bottle tops which was great as they tend to come in bright colours. Another good source is milk bottles. I preferred using HDPE as it was less brittle and easier to work, so only really used PP if I was desperate for a certain colour.

It'll take quite a while to collect enough plastic to do something with so ask around for friends and family to collect for you too, and don't be afraid so do a cheeky scavenging lap of the block on bin day!

The melting point of HDPE is around 180oC, and PP is 160oC. A bit a googling told me that plastic only gives off the toxic fumes when it burns, so as long as you only heat it to it's melting point you should be ok. I worked in a well ventilated space just to be sure.

The folks over at Precious Plastics have been a tremendous resource throughout this project, I highly recommend having a good dig through their youtube channel and website. Their methods are a little advanced, but they've designed some fantastic machines!

Step 3: Processing the Collected Plastic

Once you've collected a decent amount of bottle tops it's time to break them down into small bits.

Begin by sorting them into similar colours. Then with the sandwich press set at 180oC simply squash them flat between two sheets of grease proof paper. I weighed it down with a brick to apply a bit of pressure and within 5-10 minutes they were thin enough to cut. Carefully peel off the paper for reuse and cut up into 5mm shards with scissors. Milk bottles are already quite thin so you can go straight in with the scissors on them.

It's up to you how small you make the pieces but I liked the mottled appearance of bits around 5mm square. With a rainbow palette of colours ready to go it was time to make them into stuff!

Step 4: Making Shapes

To shape the plastic into the desired shape will involve remelting the plastic within a cookie cutter mould...pretty simple really! Cookie cutters come in loads of different shapes so your options are wide, and if you have the means you could even make one from scratch.

I found it was important to let the plastic cool under pressure or it contracted and twisted in awkward ways. So for each mould you'll need a piece of wood to slip inside the shape and squeeze it while it sets. Just trace the mould onto some ply and hack through it with a stanley knife and a little persistence (if you have a jigsaw or bandsaw use that!)

For consistent tiles you should work by weight of plastic, but you can just fill a cup to the same level if you're not too fussed.

To melt the plastic together I placed a metal cookie cutter on a sheet of grease proof paper in the sandwich press and poured in the measured plastic fragments. After leaving it with the lid closed for a few minutes the pieces began to soften and could be gently pressed flat with a bradawl (anything a bit "pokey" will do). The plastic was then left for a further 5-10mins with the lid closed to reach melting temperature so the bits of plastic would bond together.

After that just whip it off the heat and with some more grease proof paper to stop it bonding on the top, slipped the piece of wood in and clamped it down for 10mins or so to cool and set.

To separate it from the cookie cutter I slid a stanley knife down each edge and just pushed it out. The plastic should have contracted slightly as it cooled so should push out without too much of a struggle.

There's likely to be a bit of spill from around the edge of the mould but this can be trimmed off with some more careful as I picked up a couple of cuts on this step when I got complacent.

Using this technique you can use any cookie cutter shape you can get your hands on. Tessellating shapes work well as you can build them into larger sheets. Have a go, use your imagination, and be ambitious.

Step 5: Thing 1 - Lamp Shade

The first thing I made was a lamp shade. It's really hard to take pictures of lamps, but it looks great lit up and casts a rainbow of colours on the ceiling!

This basically involved making ninety-two 40mm square tiles that graduated in colour and opacity.

Through a bit of trial and error I figured out that I needed around 7 grams of plastic to make each tile. Then it was a case of getting a gradually decreasing ratio of colour to opaque (bottle top to milk bottle) for each column.

I made the tiles as described in the previous step (bit of a marathon of a task!) and drilled a small hole in each corner of each. Then with jump rings joining each tile I made them all into one continuous sheet.

I was tempted to make this into a wall mounted light box but decided to curve the sheet into a cylinder for a ceiling lamp shade. A bit of circle maths and I ended up with a circle of ply that would sit snugly inside the top of the cylinder and used jump rings to attach it. I put a low temperature energy saving light bulb in the fitting and presto!

Step 6: Thing 2 - Love Mobile

The next shape I used was hearts, and I used them to make a hanging mobile. Larger hearts hung down the middle with smaller hearts around the outside.

I wanted the large hearts to be red but I was running low for such a big volume so I did it with a combination of red/orange/milk bottle plastic. Making two of each size, I cut one of them in half and super glued it back on to make three 3D hearts to hang down the center.

To hang around the outside I made strings of smaller hearts going through a rainbow of coulours.

Hanging from a cross of doweling I thought I ended up with a pretty neat mobile!

Step 7: Thing 3 - Christmas Decorations

I also had a star shaped cookie cutter so with Christmas on the horizon I made some decorations.

Using "Christmassy" colours of gold/silver/red/green I made a variety of combinations. With a hole drilled through one of the points and some jump rings they would work well as tree decorations but I attached them to a length of ribbon at 10cm intervals to make bunting to hang across the fireplace or up the stairs.

Step 8: What's Next?

I'm pretty much tapped for HDPE for now, but I'm going to continue to collect bottle tops! I'd love to return to the project to tile a sill with an an interesting tessellating shape, or making some roofing tiles, or a window blind, etc

I'd love to see what the Instructables community come up with so please comment if you have any advice on tweaks to the tile making process, or ideas for what this can be used for, and any pictures if you give it a go yourself!

Plastics Contest

First Prize in the
Plastics Contest