prosthetists and technologists also use models as an aid to the design and manufacture of custom-fitting implants. For instance, medical models created through stereolithography can be used to help in the construction of Cranioplasty plates. In 2019, scientists at Rice University published an article in the journal Science, presenting soft hydrogel materials for stereolithography used in biological research applications. Prototyping Stereolithography is often used for prototyping parts. For a relatively low price, stereolithography can produce accurate prototypes, even of irregular shapes. Businesses can use those prototypes to assess the design of their product or as publicity for the final product. Advantages and disadvantages Advantages One of the advantages of stereolithography is its speed; functional parts can be manufactured within a day. The length of time it takes to produce a single part depends upon the complexity of the design and the size. Printing time can last anywhere from hours to more than a day. Prototypes and designs made with stereolithography are strong enough to be machined and can also be used to make master patterns for injection molding or various metal casting processes. Disadvantages Although stereolithography can be used to produce virtually any synthetic design, it is often costly, though the price is coming down. Since 2012, however, public interest in 3D printing has inspired the design of several consumer SLA machines which can cost considerably less. Beginning in 2016, substitution of the SLA and DLP methods using a high resolution, high contrast LCD panel has brought prices down to below 200. The layers are created in their entirety since the entire layer is displayed on the LCD screen and is exposed using UV LEDs that lie below. Resolutions of .01mm are attainable. Another disadvantage is that the photopolymers are sticky, messy, and need to be handled with care. Newly made parts need to be washed, further cured, and dried. The environmental impact of all these processes requires more study to be understood, but in general SLA technologies have not created any biodegradable or compostable forms of resin, while other 3-D printing methods offer some compostable PLA options. See also Fused filament fabrication (FFF or FDM) Selective laser sintering (SLS) Thermoforming References Sources Kalpakjian, Serope, and Steven R. Schmid (2006). Manufacturing Engineering and Technology, 5th edition. Ch. 20. Upper Saddle River, NJ: Pearson Prentice Hall. pp. 586–587. External links Rapid Prototyping and Stereolithography animation – Animation demonstrates stereolithography and the