Recycled PLA Sheets From 3D Printer Waste!

As a college student working at my university's makerspace, I see pounds of PLA plastic go to waste every week. Whether it’s from support material, failed prints, or constant iteration during prototyping, a lot of PLA ends up in the trash. And when you're dealing with a university lab or a print farm running multiple printers at once, that waste really adds up.

Let’s fix that!

This guide outlines a method developed by students at the University of Colorado Boulder to recycle waste PLA into flat, laser-cuttable sheets of plastic—perfect for new projects, functional parts, or even art!

While this process is designed with large-scale users in mind—like universities or 3D printing farms—anyone looking to cut down on their printer waste can benefit from it.

The process is broken down into three main steps:

1. Crushing old PLA prints and scraps
2. Pressing the crushed PLA into flat sheets
3. Laser cutting the recycled sheets for reuse

Let’s get started!

Supplies for this project include:

1. Crusher/ grinder for PLA waste (We are currently using the Polystruder GR Pro)
2. T-shirt Press with adjustable height (To melt the plastic)
3. Foam pad (allows you to better compress the melted PLA)
4. Non-stick BBQ mats (keeps melted PLA from sticking to the press)
5. Sheet of Aluminum (this will be turned into a frame for the PLA)
6. Scale (to weigh the scrap PLA)
7. Heat-resistant gloves
8. Scrap wood (keeps the PLA from warping when cooling)
9. Weights (keeps the PLA from warping when cooling)
10. Heat gun (optional to shape PLA or remove any warping)

To start, you'll need a frame to act as a mold that the PLA will fill as it melts. Any metal rectangle with your desired thickness can work for this. Ours is 1/4 inch thick.

In our case, we used a CNC mill to cut a rectangular mold from a sheet of aluminum. The goal is simply to contain the melted PLA into a consistent, flat shape—so while metal is a great option for its durability and heat resistance, it's not the only one. If you’re creative, you might find other heat-safe solutions that work just as well.

I'll be posting more detailed instructions for building a frame soon, so stay tuned!

There are a few ways to grind up your PLA scraps, depending on what tools you have access to. Some people use an old blender. You can also build your own DIY grinder — that’s what we did at first before eventually upgrading to a dedicated machine: the Polystruder.

If you have the budget, investing in a grinder specifically designed for plastics (like the Polystruder) can really streamline and automate the process.

Whichever method you choose, the key is to break your PLA down into small pieces—ideally just a few millimeters in diameter. This helps ensure even melting and a smoother final sheet.

Once your PLA is crushed and ready, store it somewhere dry until you're ready for the next step.

Now let’s make a sheet!

To form a flat PLA sheet, the best tool for the job is a T-shirt press. This is the one part of the setup I recommend purchasing rather than trying to build yourself. Any T-shirt press with an adjustable height should work — we used the VEVOR Flat Heat Press.

Here’s how to set it up:

Temperature:

Set the press to 375°F (190°C)

Time:

Set a timer for 260 seconds (just over 4 minutes)

Material Layout:

1. Place a foam mat on the bottom plate of the open press.
2. Lay a BBQ sheet (non-stick and heat-safe) on top of the foam.
3. Center your metal frame on top of the BBQ sheet — this is where the PLA will melt into shape.

Once this is ready, you’re all set to fill the frame with crushed PLA!

Placing Scrap PLA

Weigh the PLA:

Before pressing, you’ll need to weigh out your PLA scraps using this rule of thumb:

1. 1 square inch of sheet area = ~3.2 grams of PLA
2. 1 square centimeter = ~0.5 grams of PLA

This ratio has worked well in our setup, but feel free to tweak it based on your specific press, frame, or desired thickness.

Fill the Frame:

Once you’ve measured out your PLA, pour it into the frame inside the press. Here are a few tips for a good melt:

1. Try to keep the top surface of the pile as level as possible — this helps it melt evenly.
2. Overfill slightly around the edges of the frame. This ensures the corners and sides get fully filled during melting and pressing.

Finally, place another BBQ sheet over the top of your PLA pile. This prevents sticking and helps apply even heat and pressure from the top.

Now you're ready to press!

Now it’s time for the main event: making your recycled PLA sheet!

Your press should be fully heated to 375°F (190°C).

Safety First

The press will be extremely hot at this point — even the top side of the closed press can cause burns. Please wear heat-resistant gloves and be cautious when working around the machine.

First Press

1. Double-check that your BBQ sheet is still on top of your PLA pile.
2. Carefully close the lid of the press onto the pile. It should take some effort to close.
3. If it closes too easily, lower the press height (usually with a knob on top).
4. If you can’t close it at all, raise the height slightly.
5. If your press doesn’t start the timer automatically, go ahead and start it manually for 260 seconds.

Once the timer goes off, carefully open the press.

Second Press

1. With the lid now open, lower the press height by about 3–5 full rotations.
2. This step forces the melted PLA to spread fully into the corners of the frame. Skipping this step can lead to uneven thickness and air bubbles in your sheet.
3. Close the press again — it should still be hard to close, but slightly easier than the first time.
4. Start your 260-second timer once more.

After the second timer ends, open the press — you should now have a nice, flat, mostly uniform PLA sheet!

Tip:

It may take some trial and error to dial in the right amount of force. But as a general rule:

Too much pressure is better than too little.

If you don’t press hard enough, the PLA may not fully melt or bond across the sheet.

After pressing, it's important to cool your sheet properly to prevent warping.

Cooling Setup:

Make sure you have a large, flat surface next to your press ready for cooling.

1. Once the press is open, carefully slide the entire frame (with the BBQ sheets still on top and bottom) onto your cooling surface.
2. Leave the foam pad on the press — it’s not needed during cooling.
3. Place a flat wooden board (larger than your frame) on top of the upper BBQ sheet.
4. Add a few weights (books, dumbbells, etc.) to hold it all down evenly.

Let it cool for about 10 minutes before removing the sheet. This helps lock in the flat shape and prevents major warping.

Once your sheet has cooled, it’s time to remove it from the frame.

Chances are, you’ll notice some overflow PLA around the edges — this is totally normal, but it can make removing the sheet a little tricky.

How to Remove the Sheet:

1. Use a box cutter or utility blade to carefully score along the inside edge of the frame.
2. This will help separate any PLA that’s bonded over the edge and make it easier to lift the sheet out cleanly.
3. Work your way around the frame slowly — don’t rush this part, especially while using a blade.

Once released, your sheet is ready to be repurposed!

Now for the fun part!

You’ve got a fresh, flat sheet of recycled PLA — let’s turn it into something cool.

Laser cutting is the main method I’ve used to repurpose these sheets, but I’m sure there are plenty of other creative uses out there. If you're just getting started, I recommend trying something simple like keychains. I'll also share some other project ideas I’ve had success with!

Laser Settings (Tested on Epilog Mini & Epilog Pro):

PLA can be tricky to laser cut and engrave because it can become melty instead of cleanly vaporizing like acrylic does. With this said, these are the settings that work best after lots of trial and error:

Tested on 40W and 50W laser machines

1. Laser Cut:
2. Speed: 5%
3. Power: 100%
4. Laser Engrave:
5. Speed: 30%
6. Power: 100%

Make sure to keep an eye on your cuts, and use good ventilation. Some flames and slight edge melting is normal but can often be cleaned up with sanding.

Things You Can Make:

1. Keychains – A great starter project. Easy to design, quick to cut, and super satisfying.
2. Boxes – Use a tool like MakerCase to design interlocking boxes for storage or display.
3. Acrylic-PLA Signs – Combine laser-cut PLA details with an acrylic backing to make custom signs or name tags with embedded lettering or graphics.
4. Topographic Maps – These look stunning when cut from layered wood, but you can recreate the effect using stacked PLA sheets for a colorful, recycled twist! (I'll be posting a separate tutorial on how to generate topo maps for laser cutting soon.)

I want to wrap up this guide by giving credit to everyone who helped make this project possible.

This recycling method was developed by the RePLA Engineering Projects Group at the University of Colorado Boulder. Huge shoutout to the team for getting this initiative up and running and helping reduce waste in our campus makerspace!

Also, big thanks to the Teaching Tech YouTube channel — their video on PLA recycling was a huge inspiration for this project and includes a lot of great information that complements what you’ve read here.

Right now, we’re actively turning waste PLA from student projects into reusable flat sheets — and those same students are using the recycled material for their projects. It's a full circle process that I think is really cool!

If you end up building your own recycling setup based on this tutorial, I’d love to hear about it and see what you come up with! Feel free to share your process, your projects, or any improvements you make along the way.

Thanks for reading, and happy recycling!