A common criticism of 3D printers is that they're not a panacea. They can't do it all - a limitation shared by every tool, when you think about it - and because of that some vocal people claim they're worthless. You can't really convince anyone who's dead-set against being convinced, so let's move on to more interesting things. A problem being worked on right now is developing a set of technologies and workflow for microfacture - extremely small scale automated manufacture, on the scale of a hackerspace or a home workshop. Most of the components exist right now, from 3D printers to lathes and mills, but they're mostly not automated and not stitched together into a contiguous process. Enter the Cubespawn Project. Cubespawn is a project which aims to build an open source microfacture system which, like the RepRap is capable of reproducing itself. Cubespawn will eventually consist of six different modules (Printcube, Lazcube, Sawcube, Lathecube, Drillcube, and Millcube) that together comprise a fully operational portable factory. The idea is that the output of one of the modules (say, the Printcube) can be fed into other modules in the system (like the Millcube) for further processing and refinement, eventually resulting in a finished verison of whatever you're fabricating. The project's vision is an ambitious one: By bringing a Cubespawn kit into a village and hooking into existing infrastructure (photovoltaic power and recycled metal feedstock) the village can, in theory bootstrap itself into a large enough microfactory to build industrial and farm equipment. The entire system is designed to run on ROSi, the Robot Operating System (Industrial version) which has been engineered to drive general purpose industrial systems like this. At the moment the project consists of only one module and a couple of kit parts, and they're soliciting additional funds to develop the other modules.
Ordinarily I'm a cheerleader for projects like this. It's a significant undertaking to build a microfacture setup of any kind, and even wood or metal shops aren't cheap to assemble. 3D printers are rapidly advancing in capability and reliability; open source CNC routers like the Shapeoko and the Kikori are also coming down in price as they increase in capability. There are even open source laser cutters like the Lasersaur and the axCut as alternatives to relatively inexpensive commercial laser cutters like those manufactured by Epilog. From taking HacDC's laser cutter operation course and hanging out with its caretakers I feel that I should state that laser cutters are delicate, finicky beasts that require a lot of love even when purchased with support on the open market. Due to some patents that have recently expired (and the difficulty of making feedstock for them) open source laser sintering printers are on the roadmaps of a few hackers, but they're in the very early stages of development and there's no way of knowing when they'll come to pass. So, for the moment we can't bank on them. That said, my primary concern about the Cubespawn project is that they seem to be trying reinvent too many wheels to make progress in a reasonable period of time. I've seen no evidence that they're executing an "identify best of breed/incorporate/advance/publish" development loop and some evidence that they seem to starting over from scratch, which is going to delay development. I also have strong concerns about the hand-wavy "We'll just plug into an existing solar panel array for power and use aluminum recycled with a forge" part of their use case. While certainly doable neither of those things grow on trees and how widespread both photovoltaic arrays and small-scale scrap recycling in underdeveloped areas are remains to be seen.
While I'm being such a downer why not talk about another fairly sizeable pachyderm camping out in the living room and working over the party's buffet? Nanotech, or the fabrication of materials and machinery on a subcellular scale is bandied around by too many people as the answer to all of our prayers, wishes, and dreams once it gets to the point at which it goes general purpose... which, let's be honest, might never happen. That said, nanoscale materials have been showing up in consumer goods and products in significant quantities in the past decade, which means that they're being used on an industrial scale. This also means that the first ever case of nanopoisoning may have been medically documented. A 26 year old chemist found out the hard way that she was working with nanomaterials (nanoparticles of nickel about 20nm in diameter each, specifically) when, after exposure to the ultrafine dust, her respiratory and immune systems went berserk. Starting with normal-seeming allergic reactions like congestion and a runny nose, the unnamed chemist's symptoms rapidly progressed to dermal sensitivity to her belt buckle and earrings which previously had been inert. Only after prolonged absence from her workplace was her body's immune system able to gear down to a lower response level. Dr. Shane Journeay, a medical doctor and nanotoxicologist at the University of Toronto has, after reviewing the data and assessing the unknown chemist's state of health determined that she can probably never work in that building ever again if she values the remainder of her health and well being. He coauthored the case study which was published in the American Journal of Industrial Medicine. While I am not a physician (and not offering medical advice of any kind) the description of the unknown chemist's symptoms sounds an awful lot like the sensitization stage of allergic reactions induced by inhalation of the nickel nanoparticles which, due to their extremely small size and light weight could easily have been swept up by stray air currents and inhaled, whereupon they would be small enough to infiltrate individual cells in the linings of her nose, throat, and lungs and wreaked havoc.
At present there is nothing requiring that nanoscale materials need to be labelled in any way, either on the products themselves or in the workplace. Some years ago, Dr. Anders Sandberg designed warning labels for various sorts of hazards one might encounter in a posthuman future, among them one for potentially hazardous nanoparticles. I suggest that we start using these warning signs appropriately on a proactive basis.