Upcycle Acrylic Scraps Into New Sheets and Jewelry

We are going to show you the quick and dirty way to turn your old acrylic scraps from laser cutting into new sheets that you can cut some more! You basically just need panini-press or toaster and a bottle jack! Heat up the acrylic (not too much!) and then squish it between hot steel plates with the bottle jack, and in about 30 minutes you will have a new sheet of acrylic! Plus you can usually get fun combinations of colors!

If you want to learn the best ways to do this, you should check out the people who are really good at this, "Offcut Studio" https://www.instagram.com/offcutstudio/ . They are the masters of this technique and do it in a much less janky way. Plus you can hire they for an online consultation and they will tell you how to set up your acrylic recycling system well!

But if you just want to get started squishing old acrylic into new, read on!

BTW: We use the off-cuts and upcycled plastic to make jewelry and keychains that we sell to raise money for an animal rescue that we work with!

Supplies

Scrap Acrylic (like all the leftovers from laser cutting)
Oven / Panini Press / Heat Press
Galvanized / stainless steel sheets
Metal Plates
Bottle Jack (8ton)
Rigid Press frame (Build your own with this instructable!)
Plastic Shredder (optional)
Safety goggles (you are working with high pressures and heats!)
Silicone heat-proof gloves

Step 1: Background and Theory

Most folks who have a laser cutter have a big pile of acrylic scraps laying around that eventually get thrown away. BUT! You can actually fuse these pieces back together and make new sheets for cutting!

At our little lab in the rainforest (www.dinalab.net), we have limited access to resources. So we have been upcyclingas much material as possible for prototyping and making art. So we recycle a lot of plastic from the community as well as cardboard for things like laser cutting or 3D printing.

Background

For plastics, I had always assumed that acrylic sheets (PMMA) were a lost cause. This type of plastic cuts super well with a laser but isn't really thermoplastic. Instead of becoming a liquid goo when heated up, it just sort of gets a little gummy-like and then starts burning if you keep heating it. (Look at the third picture for an example of when they get heated too much)

Leif on Youtube

But then I started seeing a couple amazing things: Like this person Leif, who heated up the acrylic and then squished it into a giant block: https://www.youtube.com/watch?v=9kLUnlSEMa4&t=724s

Offcut Studio

Then even more impressive, this person, "Off Cut Studio"https://www.instagram.com/offcutstudio/ has been making gorgeous repurposed sheets out of acrylic scraps and then turning those into jewelry and other things! It looks like they have a nice proper heatpress that is much more made for this job. They also offer consulting services online you should contact if you want to get started! My tests here are much more inexperienced, and I'm absolutely sure they have MUCH BETTER advice than I do!

Theory: Heat + Pressure + Time

So I started wondering how they were able to do this? As i mentioned before, whenever I tried heating up acrylic scraps they would just get a little soft and bendable, but wouldn't stick to each other. But then I noticed in these two folks who had fused acrylic, they both had the missing element PRESSURE.

The entire key to fusing acrylic is to have it HOT and UNDER HIGH PRESSURE for a LONG TIME (at least 30 mins)

Heat

If you just heat the acrylic it won't stick together. If you heat it around 325F / 165C (at least on my paninin press) it seems to get nice and rubbery without burning.

If you try to squish it together by just putting some weights on top of it, it also won't really melt together. Instead you need a much more powerful force to start squeezing them so much that they fuse into each other.

Pressure

I don't know the exact specs on Leif or Offcut Studio's presses, but I did some quick, cheap experiments myself. First I had a 2 ton bottle jack, and did some tests and it came out OK, but sometimes the parts were still loose. I then upgraded to using my truck's 8 ton bottle jack. This seemed to work a bit easier.

Time

During my first tests, i had figured once the plastic was squished it would be fine, but this hot acrylic is springy! It needs time with the heat and pressre to slowly meld into itself. It might work after just 10 minutes, but fo realiability we have been waiting 30 minutes. Do some tests yourself and see what works!.

Step 2: Collect or Shred

The most basic way to do this is just grab whatever scraps of plastic you have laying around and toss them into the heater. But if you want more control over your work, you can first sort the acrylic by color! Also if you have a plastic shredding machine (we do luckily!) you can break down the acrylic into tinier bits that can make for an even more homogenous sheet when you melt and press them.

Also if you have wild Agoutis in your yard they are pleasant companions for sorting plastic with.

Step 3: Heat Plastic and Plates

Remember one of the keys of this process is that the plastic needs to stay heated WHILE it is being pressed. We are using the steel plates as a way to hold the heat on the acrylic while it is being smashed (They are like thermal ballast). Folks like offcut studio seem to have a cool machine that heats WHILE it is pressing which makes it a lot easier, but we are doing this the cheapo-DIY way!

So put your metal sheets onto your pannini press / other heat source. Then put your thin galvanized metal sheets on top of the thick metal plates. Then add your acrylic off-cuts or shredded acrylic. Remember you can do this with small sheets of acrylic or off-cut bits or small shreds, it all works good!

Heat everything 325F / 165C

Let the plates and the acrylic get nice and warm for about 10 minutes.

Notice i have some weights on top, these won't be enough to heat press the acrylic, but the little bit of added pressure helps get the heat into all the parts.

Step 4: Press (with Heat)

After the plates seem saturated with heat and the acrylic is nice and warm it's time to transfer it to the press!

Use some heat-proof gloves to move your hot metal+ acrylic sandwhich to your press.

Start cranking the press when everything is locked down into place. You should be able to noticably see the gap where the acrylic is getting noticably smaller. Crank your jack until you have reached the desired thickness (Usually i aim for half the original thickness of what i put in there, so i know it's been smashed well!) and then let the whole setup sit for 30 minutes.

MAKE SURE NOT TO OVERLOAD THE CAPACITY OF YOUR PRESS. That is, if you built a press yourself like we did, don't crank it so tight that the press itself might break!

Step 5: Demold and Cut Again!

Release the pressure on your bottle jack and see how it turned out! Ideally there should be no gaps and all the plastic is merged together well. If not, you can always heat it up and squish it some more!

Step 6: Package and Sell Your Upcycled Crafts

We sell all our upcycled art to help out a really nice rescue center we work with that rehabilitates endangered animals (like sloths and tapirs) https://www.appcpanama.org/. All the money we get selling these goes directly to feeding those hungry friends! Last year we raised over $2500 for them!

We open source all our designs so if you want to use our cute jungle creature designs too, please go ahead!

https://github.com/Digital-Naturalism-Laboratories/Dinalab-Keychains

We even make the jewelry holders out of old pizza boxes from a nearby bakery and have the laser cutter templates for those available to you as well!

https://github.com/Digital-Naturalism-Laboratories/Laser-Cut-Jewelry-Holders

You can use these designs to cut old cardboard (like pizza boxes) to hold earrings, keychains, necklaces, or other jewlery

Step 7: Troubleshooting

Stickiness

The acrylic can sometimes be sticky and hard to peel off the metal. One solution to this is some people put on a mold release (or you can even use non-stick cooking spray) and it will help the acrylic come off easier.

Discoloration

Our first batches we heated and pressed directly on the thick steel sheets. This worked ok, BUT sometimes the paint or rust would embed itself in the surface of our new acrylic sheets and it didn't look that great. So we cut some galvanized steel sheets as liners and the acrylic comes out nice and clean!

Too Much Pressure! Too Loose press!

DANGER! If your press is not set up well (like ours was) and the jack isn't bolted in place you can actually tighten the press TOO much and then if the plastic slips the whole press can explode sending your steel sheets flying! so MAKE SURE YOUR PRESS IS SOLIDLY PUT TOGETHER AND LOCKED DOWN to withstand the pressures you are putting it under! You can see the results in the photos above of when our jack slipped out and shot a hot steel plate across the yard! So be CAREFUL!

Step 8: Alternate Methods: Mix With Other Plastics

Maybe you don't have the equipment to heat press the acrylic properly, or maybe you don't have the time to wait for each sheet and want it quicker. There is one other approach we tried out:

instead of trying to get the acrylic to stick together, you can instead make a composite and mix the acrylic with another type of plastic that melts easier. As long as the other plastic is also safe for the laser cutter, you should be good!

We used both shredded PLA (from 3D prints) and shredded Polypropylene (PP). The acrylic laser cuts very well on its own, and the PLA and PP are a bit harder/meltier to cut with the laser cutter, so this makes it a bit like a middle ground between the acrylic and other plastics. Plus you can get nice effects where the clear acrylic parts add little windows of transparency.