Researchers from UT Austin developed CRAFT, a 3D printing method using inexpensive hardware to create complex replicas, like human hands, with varying hardness from a single material to improve medical training and protective gear
Researchers have developed a novel 3D printing technique capable of creating objects with highly diverse physical properties on a pixel-by-pixel basis. Using inexpensive, commercially available printers and a single feedstock, the team successfully fabricated a realistic model of a human hand that mimics the distinct mechanical characteristics of skin, ligaments, tendons, and bones.
The method, titled Crystallinity Regulation in Additive Fabrication of Thermoplastics (CRAFT), was detailed in the journal Science by a collaborative team from The University of Texas at Austin and several national laboratories, including Sandia National Laboratories.
Engineering complexity through light
The CRAFT method utilises a standard digital light processing (DLP) printer to transform a liquid resin called cyclooctene into solid plastic. Unlike traditional 3D printing, which often requires different “inks” to achieve varying textures, CRAFT achieves complexity by varying the intensity of light projected onto the resin.
By controlling molecular-level order in three dimensions, researchers can alter the material’s mechanical and optical properties during the printing process. High-intensity light can produce rigid, bone-like structures, while lower intensities create flexible, rubbery regions. Because the entire object is printed from a single material, it avoids the common “interface failure” seen in multi-material prints, where different substances fail to bond and peel apart under stress.
3D printing applications in medicine and safety
One of the primary applications for this technology is the creation of high-fidelity medical training models. Traditional 3D-printed models often lack the nuanced “feel” of human tissue, forcing medical schools to rely on expensive and difficult-to-source cadavers. CRAFT allows for the production of models that simulate the interconnected nature of human anatomy, such as a knee joint with moving ligaments and rigid bones.
Beyond medicine, the researchers envision using CRAFT for “bioinspired materials” in personal protective equipment. By mimicking structures found in nature, like tree bark or bone, the method can create helmets or armour with alternating hard and soft zones designed to absorb vibrations and impacts more effectively.
Accessibility and sustainability
A significant advantage of the CRAFT method is its cost-effectiveness. While many high-end multi-material printers cost tens of thousands of dollars, CRAFT is compatible with consumer-grade resin printers priced at $1,000 or less.
Additionally, the method offers a potential path toward reducing manufacturing waste. Objects made using this process can be melted down or dissolved with a solvent, allowing the material to be recast into new shapes.
