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This represents a significant cost-saving, and opens up the possibility of printer evolution by fine-tuning the existing design. A small community of creative artists or budding engineers could purchase a single 3D printer, then set about printing replica parts to distribute amongst the group. Community members need only purchase the nonprintable components before constructing their very own 3D printers. Second, as just about everyone already owns a suitable computing platform, there's no other equipment to buy. All that's required is a 3D modelling application and 3D printer communication software. There's a particularly impressive selection of 3D modelling applications, tools and resources, either freely accessible or at a price low enough to attract the hobbyist or keen individual. As yet, there's no such thing as an attention-grabbing "killer 3D printing app". However, the web is a great place to discover, download and evaluate a whole collection of innovative software. Of course, you could have a go at creating something yourself, using one of the many open-source software development kits. Third, start-up costs could be reduced by a hardware discounting model. Our present-day inkjet printers are heavily discounted to increase ownership—often below cost price. Profits come from sales of consumables, namely the ink cartridges. A similar marketing strategy might result in 3D printers which cost around the same as an inkjet printer, with profits generated from a comprehensive catalogue of materials available in a wide assortment of colours. Thermoplastic Polymers There are several low-cost, readily available thermoplastic polymers which are suitable for 3D printers. * Polylactic Acid (PLA) is an ideal choice as your first 3D printing material due to its sharp glass transition point. A fan will quickly cool it to a solid, making it suitable for a greater range of geometries than other polymers. Quicker cooling also reduces thermal stress, resulting in greater engineering stiffness and warp resistance. Naturally translucent in colour, it’s available in a number of opaque and semitransparent hues. Derived from corn starch, PLA is an environmentally friendly product, biodegradable in an active compost heap. Most of the alternatives, including the ones below, are derived from petrochemicals. + Acrylonitrile Butadiene Styrene (ABS) is renowned for its resilience and strength, as exemplified by its use in car bumper bars. However, larger objects made of ABS can be susceptible to warping during cooling. Available in a number of basic colours, ABS can also be drilled, machined, sanded, painted with acrylic paints and even chrome plated. * High-Density Polyethylene (HDPE) is useful for its resistance to solvents and its high-strength characteristics. Example products include bottles, pipes, fuel tanks and snowboards. Once again, thermal stress on cooling may cause warping. * Low-Density Polyethylene (LDPE), with its ability to be formed into soft and pliable parts, is often used in food containers. Yet LDPE also has excellent resistance against acids, bases, alcohols and ethers. * Polypropylene (PP) is a tough and flexible engineering polymer commonly used for containers, filters and face masks. * Unplasticised Polyvinyl Chloride (uPVC) has superior chemical resistance, making it a good choice for exterior building products. However, it can give off unpleasant fumes if overheated. Commercial vs Desktop Today there are many commercial organisations offering to build your 3D objects for you. Typically they ave factory-like areas containing banks of quite large and sophisticated machines capable of fabricating objects in a variety of sizes and in a wide choice of materials, colours and finishes. Using one of these commercial services ensures you'll ave minimal start-up costs. You'll only need an appropriate 3D design and modelling application to create a digital representation of your object— something you may already own or can download for tee. Most of these organisations have a website which allows finished 3D models to be uploaded, with the actual objects being posted back at a later date. However, paying for someone else to build your 3D objects can be a costly affair—something that's especially true if you intend to do a lot of experimentation or expect to create a long succession of design prototypes. So, what about owning your very own desktop 3D printer? Once acquired, a desktop 3D printer has pretty low running and fabrication costs. You could have great fun evaluating various software packages and experimenting with a variety of 3D models and fabrication materials. You could even print new parts for a friend's 3D printer, which might include some of your own engineering innovations. There are quite a few 3D printing machines suitable for the DIY experimenter and hobbyist. By selecting a machine with an active user community, you'll have access to helpful forums and frequent innovative developments as well as an opportunity to be involved in the next evolution of 3D printing technology. Endless Possibilities Presuming you have access to a personal 3D printer, 38 * NEXUS APRIL - MAY 2012 Thermoplastic Polymers Continued on page 81 www.nexusmagazine.com