WTF is... 3D printing
Roll your own
Head along to London's Design Museum  and you'll find a remarkable shoe on display until August. Called the Melonia Shoe, it’s perhaps not what most Reg Hardware readers would wear, but it is remarkable, not so much for the design, but because it was printed by Belgian product prototyping company Materialise and Sweden-based designers Naim Josefi and Souzan Youssouf.
On a grander scale, EADS in Filton, near Bristol, is using printing techniques to create titanium landing gear brackets for aircraft. It hopes soon to be able to print a whole wing.
If the boot fits: the printed Melonia Shoe
But while both may be referred to as ‘3D printing’ there’s a world of difference between the two processes, and they’re not the only ways of creating real objects from a three-dimensional computer model. So, just what is 3D printing?
It's something of a catch-all term, used to describe some very different technologies, and encompassing things like stereolithography, rapid prototyping and "additive manufacturing". But at heart, what the name conjures up is the image of a device that, once fed the right instructions, can churn out any object that you want, from shoes to aircraft parts.
In reality, that’s still some way off. While there are some machines that can use two print heads to lay down, for instance, conductive tracks as well as polymers, creating objects that use several materials, or that emerge as fully formed machines rather than components is some way off.
How does 3D printing work? The phrase 'additive manufacturing' gives the best clue: objects are built up layer by layer, based on an template created with design software.
EADS' airbike: printed from nylon powder
Imagine an inkjet printer. If it were laying down a thin layer of plastic, instead of ink, the resulting image it would represent a slice through an object. Now, if the printing surface is dropped down by the thickness of a layer, successive layers can be printed on top of each other, and the end result is a three-dimensional object, created by adding material in layers than can be below two hundredths of a millimetre in thickness.
This process is, essentially, the reverse of a traditional milling machine, which cuts away material from a solid block to create an object. One of the advantages of additive manufacturing is that there’s much less waste.
HP's 3D printing rig costs around 11 grand
One of the commonly used materials for this sort of work is a polymer, like ABS, extruded from print heads that look a little like a glue gun. You’ll find countless examples of objects like clothes hooks, cups, and fairly simply objects. But that’s by no means all that can be created, or the only way of doing it.
For objects like those titanium aircraft parts, powdered metal particles are fused together with a laser, a process known as sintering. In stereolithography, a laser focuses on the surface of a vat of polymer, causing localised hardening – you can see the process in action in this video  – and very complex designs can be created.
Clever software will even automatically add supporting structures, so that you can create designs with internal spaces or overhanging sections, either simply snapping them off or – in the case of systems like the Object Polyjet  - by flushing them out with water or dissolving them.
That, in fact, is one of the key things to remember about the current generation of 3D printing systems: many of them don’t produce a fully finished product, and require extra steps like removing supports, or curing polymers using ultraviolet light, before the object is finally ready.
3D printing isn’t the sole preserve of the professional manufacturer. There are several projects that aim to make it easy for just about anyone to print objects at home. One of the most well know is RepRap  - read more about this one on my blog . It’s not the only one: there are several similar projects, such as Makerbot  and Fab@Home .
The RepRap rig, built by Bits From Bytes
Typically open source, you can put together a printer based on one of these systems for under a few hundred pounds, or buy one ready built for under £1000. There are libraries of basic designs that you can download and create, or use as starting points for your own objects, from sites like Thingiverse .
The resolution isn’t as fine as you get with commercial printers, but even these home-brew rigs are advancing in leaps and bounds, with users turning them to tasks such as creating the tracks on circuit boards, as well as simple plastic objects.
Fangs ain't what they used to be: 3D printed gnashers
There’s also a sort of half-way house between industrial and DIY 3D printing, in the form of services such as I Materialise  where you can upload your own designs and have them printing by these companies. Or you can modify some of their examples.
Fans of 3D printing believe it has the potential to be a massively disruptive technology, but for the moment, the restrictions and costs make that unlikely. Even so, for small quantities or products, it can be cheaper than injection moulding, and it certainly makes it much easier and quicker to create prototypes. With desktop 3D printers from companies like HP starting at around £11,000, it’s potentially affordable by even relatively small operations.
Examples like the Melonia Shoe – outré though it may be – also point to other areas such as instant customisation, where digital scans can create a perfectly fitting product, based on a standard template.
More exotically, some people are experimenting with printable-yet-edible materials - Candy Fab is a DIY toffee printer project  - and even investigating living cells – though a more realistic biological application, for now, is likely to be creating replacement skeletal joints, potentially with a lattice or ‘scaffold’ structure into which real bone may grow. And 3D printing is already being used in dentistry, where it can create wax models from scans for casting crowns and bridge work.
From scan to skull: Japan's Bone Factory wants to print you a new skeleton
There are potential uses in remote areas too: biopolymers can be created from locally grown crops, allowing a 3D printing system to be used to create items that would otherwise entail a long wait, or expensive - financially and in terms of carbon output - shipping.
3D printing isn't going to make traditional manufacturing redundant any time soon, but it’s definitely a technology to watch. And, as the Melonia Shoe shows, wear. ®