3D printing has the power to change the way that we look at manufacturing products for the masses. There are so many applications within this broad technology known as 3D printing, that I simply cannot list them all. But I do want to cover some of the general applications of this technology.
3D printing is here to change the way that the "average Joe" can manufacture parts. Virtually anyone has access to this technology if he or she is knowledgeable about where to go for the services. There are quite a few local facilities around the globe. If you live in a large city, there is probably a place to use this kind of manufacturing, just as there would also be places for machining methods. There are multiple international 3D printing facilities that can manufacture custom parts and have it sent to virtually wherever you need. For example, Kraftwurx, Shapeways, Ponoko, Redeye, or whoever have access to printers in different places in the world. If you live in a large country, you can probably gain access to one of these services. Places like the United States, Great Britain, Germany, Australia, and Russia have access to these companies.
Some people are even buying their own entry level printers to make things in their garages. Companies such as 3D Systems, Makerbot, and others are making it easy for people to gain access to the technology for a reasonable price. Some of these entry level 3D printers cost around $3,000. Others cost as low as $800. It depends on what you're looking for, really. Cubify is a reasonable printer to look into. If you want to get a higher end FDM printer that has great qualities for a reasonable price, you might want to look at the Mojo printer. I could continue to ramble on about some of the other entry level printers out there, but if you're interested - the information is all over the web. The point is: you can gain access to an entry level printer for a couple thousand dollars.
Being in the 3D printing industry, I've found that most people look to use an international 3D printing facility to make parts and orders. Most people using this service have a background in 3D modeling before creating parts. This means, they have the ability to produce 3D images on the computer. The "makers" creating their own parts typically are very talented on the computer with imaging software. If they have the talent to produce a scaled down 3D model of whatever they want to produce, they can likely manufacture it through 3D printing.
Due to the availability of this technology known as 3D printing, the "average Joes" across the world are starting to produce real parts. The garage engineers are creating some cool stuff! Some of the do it yourself "makers" out there already have extensive backgrounds in engineering, but simply want to continue making things as a hobby. Regardless, 3D printing is definitely gaining momentum, and people all over are using it to manufacture some cool stuff!