Imagine a future in which a device connected to a computer can print a solid object. A future in which we can have tangible goods as well as intangible services delivered to our desktops or highstreet shops over the Internet. And a future in which the everyday "atomization" of virtual objects into hard reality has turned the mass pre-production and stock-holding of a wide range of goods and spare parts into no more than an historical legacy.

Such a future may sound like it is being plucked from the worlds of Star Trek. However, while transporter devices that can instantaneously deliver us to remote locations may remain a fantasy, 3D printers capable of outputting physical objects have been in development for over two decades and are starting to present a whole host of new digital manufacturing capabilities. 3D printing may therefore soon do for manufacturing what computers and the Internet have already done for the creation, processing and storage of information. Such a possibility is also starting to receive attention in the mainstream media. The Economist, for example, recently published this great article on The Printed World.

The following provides an overview of 3D printing technologies and their present and likely future application. For a full list of 3D printer manufacturers, as well as initiatives and organizations pioneeering their application, please see my 3D Printing Directory.

Current Technologies

3D printing is an additive technology in which objects are built up in layers and usually over several hours. The first commercial 3D printer was based on a technique called stereolithography. This was invented by Charles Hull in 1984. Stereolithographic 3D printers (known as SLAs or stereolithography apparatus) position a perforated platform just below the surface of a vat of liquid photocurable polymer. A UV laser beam then traces the first slice of an object on the surface of this liquid, causing a very thin layer of photopolymer to harden. The perforated platform is then lowered very slightly and another slice is traced out and hardened by the laser. Another slice is then created, and then another, until a complete object has been printed and can be removed from the vat of photopolymer, drained of excess liquid, and cured. Stereolithographic printers remain one of the most accurate types of hardware for fabricating 3D output, with a minimum build layer thickness of only 0.06mm (0.0025 of an inch).

Another common commercial 3D printing technology is fused deposition modelling (FDM). Here a hot thermoplastic is extruded from a temperature-controlled print head to produce fairly robust objects to a high degree of accuracy. A key benefit of this technique is that objects can be made of out of exactly the same thermoplastics used in traditional injection molding. Most FMD 3D printers can now print with both ABS (acrylonitrile butadiene styrene) plastics, as well as a biodegradable bioplastic called PLA (polylactic acid) that is produced from organic alternatives to oil.

A third well established technology is selective laser sintering (SLS). This builds objects by laying down a fine layer of powder and then using a laser to selectively fuse some of its granules together. At present, SLS 3D printers can output objects using a wide range of powdered materials. These include polystyrene, nylon, glass, ceramics, steel, titanium, aluminium and even sterling silver. During printing, non-bonded powder granules support the object as it is constructed. Once printing is complete, most excess power is then recycled. A closely related 3D printing technique to SLS is known as selective laser melting. This uses a laser to fully felt the powder granules that form a final object, rather then just heating them enough to fuse them together. As yet another variant, a technique called selective heat sintering (SHS) uses a thermal print head -- rather than a laser -- to apply heat to successive layers of a thermoplastic powder, and as explained in depth here.

Finally in common application there is multi-jet modelling (MJM). This again builds up objects from successive layers of powder, with an inkjet print head used to spray on a binder solution that selectively glues only the required granules together. Some MJM printers -- such as the ZPrinter 650 from ZCorp -- can spray on four different colours of binder solution, so permitting them to create full-colour 3D objects at up to 600x540dpi. You can watch a great promotional video for the ZCorp 650 here.

Commercial 3D Printers and Online Services

A wide range of commercial 3D printers for industrial application are now available from companies including 3D Systems (which works with most technologies and is rapidly acquiring many smaller manufacturers), Stratasys (which initially developed FDM), Fortus and Dimension Printing (which use the Stratasys FDM process), Solid Scape (which uses its own FDM process but is now owned by Stratasys), and ZCorp (which specializes in MJM as noted above). Another major player is envisionTEC whose PerfactoryXede and PerfactoryXtreme 3D printers achieve a better surface quality than obtained with other technologies by projecting voxel datasets into a photopolymer. (A video that shows how this voxelization process differs to layered technologies can be found here).

All of the above producers of 3D printers have built their growing businesses from scratch in the rapidly expanding 3D printing marketplace. However, traditional 2D printer manufacturers are now also starting to dip their toes into 3D waters. For example, Hewlet Packard (HP) now sells its FDM-based HP Designjet 3D printer series having done a deal with Stratasys.

Prices for most commercial/industrial 3D printers tend to start in the ten-to-twenty thousand pound bracket and spiral upwards. Although some desktop models are on the market, most commercial 3D printers are usually fairly bulky and often floor-standing. It is, however, already possible for lone designers and private individauls to obtain high quality 3D printouts from commercial 3D printing hardware by using an online bureau. For example, Sculpteo, Shapeways and 3D ProParts allow anybody to have their designs 3D printed and marketed online. The first two of these firms even offer a facility to upload two photographs of yourself from which a full-colour figurine will be created! Online 3D printing services can also be obtained from Industrial Plastic Fabrications Limited.

Personal 3D Printing

For home enthusiasts and lone inventors who want to start 3D printing themselves, a growing range of personal 3D printing initiatives, kits and printers are also now available. For those seriously into real DIY, there are two open source 3D printing initiatives. Called RepRap -- which stands for the Replicating Rapid-prototyper -- and Fab@Home. These initiatives are both based around online communities that use the web to share all designs and other information required to build a printer.

For those not keen or able to scratch build, several companies now sell 3D printer kits, often based on the above RepRap designs. For example, BitsfromBytes.com sells its RapMan 3.1 3D printer kit from £795, and its pre-assembled BFB-3000 3D printer starting at under £2,000. RepRap Central is also a great supplier of 3D printer kits costing from £599 upwards. In addition to several RepRap models, these include the MakerBot Thing-O-Matic.

For those who do not want to build their own 3D printer, pre-assembled personal hardware is now also available. These include an assembled MakerBot, the BotMill Glider 3.0 (which is also available as a kit), and the excellent UP! Personal Portable 3D Printer. The latter is a truly plug-and-play FDM 3D printer that can be up-and-running 15 minutes after being unpacked, and does not require any calibration by its user. There is a fantastic video about the Up! 3D printer here. Most recently, the Cube Personal 3D Printer has been launched as part of Cybify. This sells for $1,299 and can print about 10 models from each $49.99 plug in cartridge of ABS plastic (10 colours are available!).

Current 3D Printing Applications

Most current 3D printers are not used to create final consumer products. Rather, they are generally employed for rapid product prototyping, or to produce moulds or mould masters that will in turn allow the production of final items. Such printing of 3D objects already enables engineers to check the fit of different parts long before they commit to costly production, architects to show detailed and relatively low-cost scale models to their clients, and medical professionals or archaeologists to handle full-size, 3D copies of bones printed from 3D scan data. There are also a wide range of educational uses.

The range of products that have employed 3D printers in their design process or to produce final moulds or mould masters is constantly growing. To date such products include automobiles, trainers, jewellery, plastic toys, coffee makers, and all sorts of plastic bottles, packaging and containers. You can even now purchase a 3D printed Sad Keanu Reeves. More usefully, some dental labs have for some years been using 3D printers to help create appliances, with envisionTEC selling its Perfactory Digital Dental Printer for use in the creation of crowns, bridges and temporaries by dental technicians. Using this technology, even long-term temporaries can now be created, meaning that 3D printers can quite literally already print you new teeth! envisionTEC 3D printers are now also widely used by many major hearing aid manufacturers to produce ear molds and shells for final consumer use.

Direct Digital Manufacturing

Whilst most 3D printers are currently used for prototyping and in pre-production mould making processes, the use of 3D printing to manufacture end-use parts is also now occurring. This is becoming known as direct digital manufacturing (DDM). As Fortus explain, for low-volume manufacturing DDM is more cost-effective and simpler than having to pay and wait for machining or tooling, with on-the-fly design changes and just-in-time inventory being possible. For example their customer Klock Werks Kustom Cycles builds one-of-a-kind motorcycles using a Fortus 3D printer to directly digitally manufacture some of the required custom parts.

Another company using 3D printing to create final products is Freedom of Creation (and which was recently acquired by 3D Systems). Their range of incredible, designer 3D printed products includes lighting, furniture, trays, bags and jewellery. In a similar vein, a company called Make Eyewear is now manufacturing customiziable and designer sunglasses using 3D printers.

It is also already not just a few specialist plastic items that are being made using a 3D printer. For example, engineers at the University of Southampton recently 3D printed a flyable aircraft (well, aside from its electric motor). This said, Rolls Royce are currently running a project called MERLIN with the goal of using 3D printing in the manufacture of civil aircraft engines. A driveable prototype of a new electric car called the Urbee has also been 3D printed.

Future 3D Printing Applications

Whether or not they arrive en-mass in the home, 3D printers have many promising areas of potential future application. They may, for example, be used to output spare parts for all manner of products, and which could not possibly be stocked as part of the inventory of even the best physical store. Hence, rather than throwing away a broken item (something unlikely to be justified a decade or two hence due to resource depletion and enforced recycling), faulty goods will be able to be taken to a local facility that will call up the appropriate spare parts online and simply print them out. NASA has already tested a 3D printer on the International Space Station, and recently announced its requirement for a high resolution 3D printer to produce spacecraft parts during deep space missions. The US Army has also experimented with a truck-mounted 3D printer capable of outputting spare tank and other vehicle components in the battlefield.

3D printers may also be used to make future buildings. To this end, a team at Loughborough University is working on a 3D concrete printing project that could allow large building components to be 3D printed on-site to any design, and with improved thermal properties.

Another possible future application is in the use of 3D printers to create replacement organs for the human body. This is known as bioprinting, and is an area of rapid development. You can learn more on the bioprinting page, or see more in my bioprinting video or the Future Visions gallery.

Another potential arena of 3D printing application is in the culture industries. Sculptor Bathsheba Grossman already uses 3D printers to create her works. In the future, museums could also print out exhibits as required from their own digital collection, or indeed from a global archive of artworks scanned from long-lost or too-delicate-to-display originals. You can find out more about 3D artworks, including a great video, on the Singularity Hub.

A Solid Tomorrow

In an age in which the news, books, music, video and even our communities are all the subjects of digital dematerialization, the development and application of 3D printing reminds us that human beings have both a physical and a psychological need to keep at least one foot in the real world. 3D printing has a bright future, not least in rapid prototyping (where its impact is already highly significant), but also in medicine the arts, and outer space. Desktop 3D printers for the home are already a reality if you are prepared to pay for one and/or build one yourself. 3D printers capable of outputting in colour and multiple materials also exist and will continue to improve to a point where functional products will be able to be output. As devices that will provide a solid bridge between cyberspace and the physical world, and as an important manifestation of the Second Digital Revolution, 3D printing is therefore likely to play some part in all of our futures.

For a fascinating glimpse at a wide range of amazing and unusual printers -- including concrete printers, glass printers, bioprinters, and printers that print on toast! -- click here. You may also find interesting the website Fabbaloo.com, which is dedicated to personal manufacturing and 3D printing.

Please see my 3D Printing Directory for a full list of 3D printer manufacturers as well as those projects and organizations pioneeering their application. More information on 3D printing can also be found in my book 25 Things You Need to Know About the Future. The 3D printing web references from this book can also be found here.