Custom 3D printing colors for pennies

Researchers hack colors from recycled waste using open source software they have developed and shared with the world for free. The results allow anyone to make custom colored additive manufacturing feedstock from waste plastics. Published in Advanced Manufacturing, this breakthrough paves the way for economic distributed recycling of waste plastic into low-cost 3D printed products.

A new study in Advanced Manufacturing shows how to make recycled plastic pretty again with custom colors. Researchers at by Western University in Canada, have released a free and open source software package called SpecOptiBlend. Software engineering graduate student Kimia Ketabforoosh combined her coding ability with her experience in color theory to bring more value to a new recycling technology.

Recyclebots allow people to recycle waste plastic directly by 3D-printing it into valuable products, at a tiny fraction of their normal cost. As consumers worry about being able to afford basic products as the U.S. tariffs destabilize the economy making products for themselves makes a lot of economic sense. This approach is called distributed recycling and additive manufacturing, or DRAM for short.

DRAM allows you to make custom products for less than the sales tax on conventional consumer products. Millions of free 3D-printable designs already exist – everything from learning aids for kids to household products to adaptive aids for arthritis sufferers or even walkers. Prosumers are already 3D-printing these products, saving themselves collectively millions of dollars.

“We have pushed plastic recycling to the next level, because now you can get custom colors for your 3D prints that are not even available on the market”, explains Professor Joshua Pearce, the Thompson Chair in Innovation at Western University.

“In the past you either had to be happy with the colors your waste plastic came in or mix them together and get boring grey”, explains Pearce. 

Plastic recycling doesn’t normally work well in the centralized context because of the low-density and value of plastic. The new approach here repurposes discarded prototypes or any other type of plastic waste back into the printing cycle with desired colors, allowing for a broader spectrum of colors and gradients.

For example, Pearce says “Western’s University’s color is a very specific regal purple. Purple 3D printing filament exists commercially but looks more like purple for Barney the dinosaur. We were able to match Western’s purple nearly perfectly”.

Another color the team matched was pink petals of the wildflower bouquet LEGO set. Literally, any color you might want is possible.

To do this, waste plastics are quantified after processing for spectral reflectance, then Kubelka-Munk theory provides the initial estimate for color mixing, which is baked into the cake of the free software. Western researchers tried three discrete optimization techniques: Nelder-Mead, Limited-memory BFGS with bounds, and Sequential Least Squares Quadratic Programming. To determine the optimal method, assessment criteria include the application of root mean square (RMS) and the color difference (ΔE CIE-2000). The research showed the Nelder-Mead method gave the optimal balance between the precision of color differences and the RMS, essential for producing high-quality colors. This research has provided a free tool that will now enable prosumers to convert their plastic waste into specific custom colors to enable DRAM.   

Using commercial plastic, MyMiniFactory users saved over $4 million in one month alone  just by making toys themselves, instead of purchasing them. A previous study by Pearce, showed consumers can invest in a desktop 3D printer for around $250 and earn a return on investment of over 100% by making their own products. The return on investment goes higher if they use recycled plastic. For example, using a recyclebot, a waste plastic extruder, on waste computer plastic makes it possible to print 300 camera lens hoods for the same price as a single one on Amazon.

“There is no question that 3D printing and distributed recycling have matured to the point that consumers can make their own products for far less money than the market can provide. Now with open source technology we can make a greater range of products including an infinite range of custom colors. I am really excited to see what people make and share.” concludes Pearce.

This paper “Creating custom 3D printing material colors using optical modeling of waste plastic” was published in Advanced Manufacturing.

Aghamohammadesmaeilketabforoosh K, Givans J, Woods M, Pearce J. Creating custom 3D printing material colors using optical modeling of waste plastic. Adv. Manuf. 2025(2):0007, https://doi.org/10.55092/am20250007.

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