Let’s say you wanted a new bike. You’d go to the shop, pick one out, buy it, and later find aspects you’re not quite satisfied with. But, you’ve already paid a lot of money so you should just put up with the small disappointments .

Now imagine the distant future, where you download a design onto your computer, input the measurements, choose the color, and then print a brand new bike into existence in front of your very eyes. Not satisfied with it? Alter the design and print out another one.

This all may sound like science fiction, but this scenario from the distant future actually happened in March 2011. Scientists printed a fully working bicycle, whole, from a 3-D printer.

It was made of nylon, weighed less than half a normal bicycle, and was reported to be as strong as steel. Unlike the process of assembling a bike in a factory, different parts such as gears , pedals , and wheels were printed as a part of the finished bicycle, not connected separately.

3-D printing is based on the principle that any 3-D object is, in essence , made up of many 2-D layers. A thin, powdered layer of the desired material is laid out on a printing tray. Then, a special binding fluid is released, which fuses areas of this powder together into a cross section of the desired item. After the first layer of the cross section is done, the printing tray drops a fraction of a millimeter, and a new layer of powder is applied. Repeating this process results in the gradual formation of a complex shape. For materials such as metals or glass, a laser is used to fuse areas of the powdered layer into shape.

The impact and application of this technology is projected to affect the world economy at its very core. Mass production will become superseded by the ability to customize a product to suit personal needs at no extra expense and at home rather than in a factory. In fact, a basic 3-D printer actually costs less than a laser printer did in 1985, meaning that this is one piece of science fiction that is already a big part of economic reality.

話說你想要一台新腳踏車。你會去商店，選一台，買下來，然後發現你有一些不太滿意的地方。但都已經花了一大筆錢買了，也最好只能忍受這些小小的失望。

現在想像一下，在遙遠的未來，你可以下載設計版型到電腦上，輸入尺寸、選擇顏色，然後就在你眼前列印一台全新的腳踏車出來。不滿意？換一種設計，再印一台吧。

這聽起來很像科幻小說，但是這個來自遙遠未來的劇本，已經在2011年3月真實上演。科學家利用3D印表機列印了一整台具備所有功能的腳踏車。

這台腳踏車是由尼龍構成，重量不到一般腳踏車的一半，報告顯示它具有不鏽鋼的強度。和工廠組裝腳踏車的流程大不相同，諸如齒輪、踏板、輪子等零件都是跟著腳踏車一起列印出來，而不是由分開的零件組裝。

3D印刷依循的原則是，任何3D物件本質上都是由許多2D平面所組成。首先在列印平台以想要的材質鋪好一層薄粉，然後釋出一種特別的接著劑，把粉層連接成未來成品的橫截圖。第一層橫截圖完成後，列印平台就會往下移1公厘，以便將新的粉層疊上第一層。重複這個流程，一個複雜的形體就會漸漸形成。當處理金屬或玻璃材質時，就以雷射來熔接粉層並且塑型。

這個技術的影響和應用，預計將會改變全球經濟的核心。這種方式將取代大型製造，它既可客製化、符合個人需求又不需多花錢，可在家製作，而不用到工廠。事實上，現今一台基本型3D印表機的價錢，其實還不到1985年時一台雷射印表機的價錢，可以想見，原屬於科幻小說的工具，已經成為經濟事實的一大部分了。