David Mellis, who occupies his time at MIT’s Media Lab, has provided all the plans needed for someone to build their very own cell phone. Notice that we are talking an actual mobile phone, like the type you make phone calls with, not a smartphone that does everything else.
The plans allow for either an LCD display or LED matrix display (a-la old-school Motorola flip phones from the early 1990s). The plans also allow for charging the battery via mini-USB, probably a cost consideration, though enterprising individuals will likely be able to adopt a micro-USB if they want.
The circuit board can be printed via OSH Park, where $60 gets you three copies (which could come in handy if you mess up and melt something). The case materials are up to your imagination, wood, plastic, whatever you can create that will enclose the other parts. Using a laser cutter for the wood is not a bad idea. You will also need to be able to handle a fair amount of hand-soldering. All told, to cover the basics, it should cost about $200-ish out of pocket.
Once you are done, pop in a standard sized (now mini) SIM card from either AT&T or T-Mobile (it has also been tested in Europe, India and China), and you have an honest to goodness cell phone. If any of you decide to build one, send us your progress, pictures and tell us the story of how it all came together, and most importantly, that it works.
The "Do It Yourself" Cellphone
sources: MIT Media Lab via The Verge
photos: Copyright of David Mellis, republished under the Creative Commons license. The images have been cropped.