Print to fit

Printing: It's not just for paper anymore. For years, engineers and designers have used rapid-prototype machines-essentially, fancy printers-to turn designs into small, lightweight 3D models, a process which eliminates the need to send designs off to an expensive prototyping plant and wait for their return. The machines work by "stacking" many layers onto one another, which build up until a three-dimensional shape appears. And as 3D printing technology advances, companies are finding new applications for it, especially with falling prices: Though some of the machines are expensive, one called MakerBot can be built from a kit and costs as little as $650.

Bespoke Innovations, located in San Francisco, uses 3D printing technology to create inexpensive prosthetic limb casings-the customer and the company work together to create a design and generate a computer model, and then the printer lays down plastic layers, one on top of the other, until the casing is formed-much like a cake with hundreds of very thin layers. Other companies have made things like jewelry, bottles, lamps, architectural models, iPhone cases, and doorknobs. Because 3D printers create objects that are relatively inexpensive and quick to produce, designers who use 3D printers can afford to try new, innovative designs with less risk: Bespoke is working on making entire limbs, which will cost as little as one-tenth of those produced by competitors-and will be dishwasher-safe, too.

Flight timing

Dozens of websites can help you compare airline prices, but sometimes it's hard to spot the ideal option on a text-filled web page. Hipmunk (hipmunk.com) makes the process easier for visual learners. Tell Hipmunk where you want to go and when, and the website will return a list of flights plotted across a timeline. Sort by number of stops, duration, price, or "agony"-a combination of all three-to decide which flight you want to take. You can even enter "tomorrow" if you like, though if you enter "yesterday," Hipmunk helpfully reminds you that it doesn't support trips to the past-yet.

WiFi bypass

Bad cell-phone reception sometimes turns iPhones into just incommunicative iPods. But iPhone, iPad, or iPod Touch users can now purchase an app called Line2, which costs about $1 and operates entirely over WiFi, so they can make phone calls from anywhere with a wireless internet signal. Line2 gives devices a phone number (or a second number), and calls don't count toward the allotted minutes from mobile providers. This might be particularly useful for people who spend much of their time on campuses or in workplaces with wireless networks. Service is $9.95 per month, which includes unlimited calling to the United States and Canada.