Growth Trends and Advances in Rapid Prototyping

This paper was co-authored by Terry Wohlers and presented in November 2001 at EuroMold in a conference titled "New Developments and Trends in RP Around the World."


Few new technologies have impacted product development as much as rapid prototyping (RP). Globally, organizations continue to discover creative uses for the technology that extend beyond prototypes and models to tooling and manufacturing. Many new developments are underway that could have a strong commercial impact. Some of these advances are so interesting that users, analysts, and vendors are on alert. As this class of technology develops, it will further expand into industries that have largely ignored or resisted it.


Industry consultant, analyst, and author Terry Wohlers is president of Wohlers Associates, Inc. (, an independent consulting firm he founded in 1986. He has authored more than 250 books, articles, reports, and technical papers on engineering and manufacturing automation. In October 2001, Terry served as analyst in a fast-paced morning television show in the U.S., and twice, has been on German radio. His appetite for adventure has driven him to climb the Great Wall of China, hike the rain forests of New Zealand, dive among sharks in Belize, bathe in the Dead Sea, and encounter lions and rhinos in Africa.

Todd Grimm is marketing manager at Accelerated Technologies, Inc. (, a rapid prototyping service provider. He joined the RP industry in 1990 and has been with ATI since 1995. He has a Bachelor of Science degree in mechanical engineering from Purdue University and has held technical positions in the CAD/CAM industry. Todd is an accomplished author and speaker and is a member of the advisory committee for SME’s annual Rapid Prototyping & Manufacturing conference. Todd is also key contributor to Wohlers Report and a monthly columnist in Time-Compression Technologies magazine.


When Chuck Hull invented stereolithography (SL) and founded 3D Systems, he envisioned many uses of the technology. However, even he could not anticipate all of the applications of SL and competing technologies. Today, methods of rapid prototyping are being used in applications and in industries that range from dentistry, orthodontics, and medicine to Hollywood filmmaking, hearing aid production, and MicroElectroMechanical Systems (MEMS). The following examples are offered with the intent of capturing the breadth of new and unusual applications worldwide.

Dentistry. In September 2001, it was announced that Cynovad of Montreal, Canada, had signed an agreement to purchase several hundred ThermoJet printers from 3D Systems. Cynovad is the exclusive reseller of these machines to the more than 50,000 dental labs around the world for the production of crowns, bridges, and other types of dental restorations. The machines produce wax patterns needed for the investment casting process. 3D Systems is delivering the printers to Cynovad re-branded as the WaxPro.

Formula 1 racecars. In England, a service provider named 3T RPD is using RP to supply parts for the Jordan-Honda Formula 1 racecars. Some of the 20 different parts are used as prototypes, but many are produced as final production parts for cars built to win races. These parts include replacement panels that form aerodynamic skins, cooling ducts, and electrical boxes. According to 3T RPD president Tim Plunkett, the company is supplying Jordan-Honda with an average of 35 laser-sintered parts per week with a typical deliver of only 48 hours. This is especially impressive when it can take two days just to receive a quote for tooling.

Custom filters. Using 3D Printing (3DP) technology from the Massachusetts Institute of Technology (MIT), Specific Surface of Franklin, Massachusetts, is manufacturing highly complex ceramic filters that are applied to everything from making soy sauce to filtering diesel emissions. One of its most intricate and impressive filters is used in heat exchangers. Another product replaces filter bags in pulse jet fabric filters where operating temperatures are up to 600°C. Using its CeraPrint process, Specific Surface produces filters in quantities of 10 to 100,000.

Artificial limbs. An estimated 1.5 to 2 million lower limb amputees live in the U.S., with 60,000 to 80,000 new amputees every year. Due to changes in the shape and size of an amputee’s stump, it is necessary to obtain a multiple sockets (artificial limbs) over a lifetime, so hundreds of thousands of sockets are required each year.  To address this demand, Bill Rogers of the University of Texas at San Antonio, USA, has conducted a study sponsored by the Veteran’s Administration. The goal is to determine whether selective laser sintering (SLS) can produce superior sockets for below-the-knee amputees. Clinical results indicate that the amputees were pleased with the fit, comfort, and functionality of the sockets, so this work is expected to continue.

Medicine. Therics, Inc. of Princeton, New Jersey, USA, uses its 3DP license from MIT to manufacture medical products that include time-released, customized, oral medications, resorbable “scaffolding,” and implants for cartilage, tendon, and bone substitutes. Therics makes it possible to produce resorbable tissue structures, such as a bone graft or a rebuilt eye socket, from CT scan data using the company’s proprietary CADLink conversion process and TheriForm 3D printing process. The structures are built from powdered natural or synthetic bones, with the latter being either bioceramic or bioglass, and they may include drugs, growth factors, and gene fragments to promote cell regeneration.

Toxicology studies. Doug Greenwood of Product Development Service of Durham, North Carolina, USA, has used DSM Somos’ WaterClear material to model a human nasal passage for CIIT Centers for Health Research. The transparency of the cured photopolymer permits visualization of air and particulate flow for improved understanding of chemical interaction with the nasal membrane. Both companies believe that the complexity of this internal passage makes it nearly impossible to physically model in any method other than RP.

Miniature parts. RP processes from around the world are producing very small parts, some as tiny as a red blood cell. The University of Southern California is using a process it calls electrochemical fabrication that electro-deposits nickel layer-by-layer using a masking technique. With this method, it is possible to produce mechanisms that measure 100 microns (0.004 inch) in height, which is about the thickness of a sheet of paper.

In Germany, a company named microTEC can produce 150 miniature photopolymer parts per hour using its proprietary stereolithography process. Layers are an amazing 1-micron (0.00004 inch) in thickness.

Researchers at Osaka University in Osaka, Japan, are using two lasers and liquid photopolymer to produce small parts using voxels rather than layers. Remarkably, they were successful in producing a detailed representation of a bull that measures 10 microns from tail to nose—the size of a red blood cell.

World’s smallest robot. Using stereolithography, Sandia National Laboratories of Albuquerque, New Mexico, has built what they believe is the world’s smallest untethered robot. The mobile unit weighs less than 28 grams (1 ounce), measures 4 cubic cm (0.25 cubic inch), and could be equipped with a miniature video camera, microphone, and wireless two-way communications. The tiny robot might be used to gather intelligence, according to the National Lab, a facility that protects U.S. military and economic interests.

Hearing aids. Many of the major manufacturers of hearing aids are in the early stages of using RP to mass customize their products in impressive volumes. Some of these companies produce more than 1,000 in-the-ear hearing aids per day. To fit the patient’s ear canal, each product is unique in its shape and size. The process begins with a silicone rubber impression of the ear. The impression is then digitized with an optical scanner, which leads to an STL file and RP for the rapid production of the hearing aid shell.

Injection mold design. Companies are discovering that they can take advantage of color 3D printing from Z Corp. to help them optimize the design of injection molds. Using mold filling simulation software, such as that from Moldflow, it is possible to output files that can be read into Z Corp.’s Z406 and Z402 color 3D printers. The result is a model that visually represents mold filling and cooling characteristics, which is a powerful aid for design and evaluation amongst tool designers, toolmakers, and injection molders.

Burn masks. RP is being using to produce custom-fit masks for burn victims. The process begins by digitizing the patient using non-contact optical scanning. The scan data is used to produce an RP model of a mask that fits perfectly to the patient’s face. The mask applies pressure to the face to slow the flow of blood to the healing skin. This, in turn, reduces the formation of scar tissue.

Developments and Trends

These examples highlight just a few of the developments in RP and some of the new and exciting applications. This information, coupled with research into ongoing developments, illustrates several interesting trends.

RP for the production of finished manufactured parts. Bell Helicopter is using RP to produce metal castings for its helicopters. Technikon Free State of Bloemfontein, South Africa, is using laser sintering to manufacture a device used at fitness centers to measure blood pressure, body fat, and weight. A user of the FDM Titan machine from Stratasys produced a replacement pulley in polycarbonate for an industrial belt sander.

Growing demand in the medical industry. Andy Christensen of Medical Modeling LLC of Golden, Colorado, USA, said the demand for RP models in the medical industry has doubled over the past 2-3 years. Yet, he believes that 90 to 95 percent of the market remains untapped. Already, orthodontics company Align Technology of Santa Clara, California, has produced more than 1 million RP models using its stereolithography machines. Align is purchasing up to 50 SLA 7000 machines for use with its Invisalign system, a process of producing invisible plastic aligners for straightening adult teeth. Separately, Interpore Cross International, a medical device company, is using seven ModelMaker machines from Solidscape to manufacture spinal implants.

Color. Z Corp. is leading the way, and others are sure to follow. Color can be used to distinguish parts in complex assemblies. It can also be used to make the exterior housing of a product, such as a cellular phone, look similar to the finished product, complete with colored buttons and other features.

Material advancements. New materials, such as WaterClear, are enabling companies to create models, prototypes, and series production parts that were before expensive or impractical to build. With some RP materials approaching the aesthetic and functional qualities of popular injection-molded thermoplastics, companies can push the limits to levels unheard of not long ago.

Micro parts. With computers and hand held electronic devices shrinking, the appetite for small parts grows. RP’s style of building parts in layers, coupled with lasers, makes it possible to produce very small parts and assemblies that are highly complex. The number of activities in this area suggests that a trend in the production of miniature parts using RP is developing.

Perhaps the most promising trend is that all of these applications may become more affordable. Recent developments have yielded RP systems that are significantly lower in price. This is true even in technologies that produce parts in photopolymers. Objet Geometries Ltd. of Rehovot, Israel, is using 1536 jets to deposit and harden photopolymer, layer by layer. Another company is hard at work developing an alternative method of quickly and accurately depositing and hardening photopolymer in a way that may surprise many.


The range of new and usual applications of RP continues to expand. These uses, combined with the many new developments and innovations around the world, are leading to advances and trends that are reshaping the RP industry as a whole. Brace yourself because this is only the tip of the iceberg. Growth into new markets and industries will redefine the role of RP and this will redefine our future.

Copyright 2001 by Terry T. Wohlers