The difference with a 3d moulder being that, instead of taking a couple hours to 3d print a mould, then stop your production line and manually install the new mould in place of the old, then start it back up again you could effectively instantly form 3d mould (via microactuators or whatnot), do a 15 minute production run and make a couple hundred parts, then move on to mass producing the next part you need with no break in-between. Your "factory" could be in full production mode nonstop yet have a single line produce many dozens of different types of parts over the course of a day.

When one thinks of space colony applications, it quickly becomes clear how essential such a thing will be. Even if you try to simplify, you're still going to have tends to hundreds of thousands of types of parts that will wear out with time. Let's say 100k unique types of of parts with a mean lifespan of 3 years - that's probably pretty realistic for a colony. That means you'll have to produce a new type of part every 15 minutes nonstop - with quantities varying from one-offs to the tens of thousands, depending on the part. Now think of how big your typical production line is and how much mass that means transporting from earth. Clearly, rapid production flexibility is critical! (same applies to all steps of the chain, including robotic assembly)

(and yes, I know a single moulder or whatnot cannot achieve all possible production jobs, real production lines involve many types of materials and many processes... it's just an example of a common production mechanism :) )

(as another side note, it should even be possible to make 3d moulds for metals. Carbon fiber cloth - or better, graphite fiber cloth - can tolerate temperatures hotter than many metals, but still has stretch and could be shaped with an array of actuators).

There are tons of online services already like iMaterialize and Shapeways - they do really excellent work.

They're saying that it won't break because that's not the purpose here. The description of the experiment is:

In addition to safely integrating into the Microgravity Science Glovebox (MSG), the 3D Print requirements include the production of a 3D multi-layer object(s) that generate data (operational parameters, dimensional control, mechanical properties) to enhance understanding of the 3D printing process in space. Thus, some of the prints were selected to provide information on the tensile, flexure, compressional, and torque strength of the printed materials and objects. Coupons to demonstrate tensile, flexure, and compressional strength were chosen from the American Society for Testing and Materials (ASTM) standards. Multiple copies of these coupons are planned for printing to obtain knowledge of strength variance and the implications of feedstock age. Each printed part is compared to a duplicate part printed on Earth. These parts are compared in dimensions, layer thickness, layer adhesion, relative strength, and relative flexibility. Data obtained in the comparison of Earth- and space-based printing are used to refine Earth-based 3D printing technologies for terrestrial and space-based applications.

The description is not "Print out a wrench so that crew members can change a rusty lug bolt". And yes, also from the description page, they include direct metal printing as part of their list of ultimate goals with 3d printing in space research.

3d printing has tons of applications here on Earth. However, this does not include general-case home 3d printing. Unfortunately, that's what most people here on Slashdot want to judge it by.

Indeed. 3d printing is not going to be suitable for mass production, for keeping a whole colony supplied in bulk components.** But for small specialty parts, it seems like an obvious answer to that piece of the equation. As the tech advances, it's just going to get more and more capable. I'm personally looking much forward to seeing whether a 3d printer that works based on thermal spraying would work out - then your production material choice would be almost limitless, pretty much any powder or small fibers you can think of that can be made to merge with the substrate through any custom combination of either temperature or velocity, and your balance between deposition rate and precision could be chosen just by rotating through nozzles of different sizes, none of the feed mechanism or material storage or anything. Your same printer could even paint, coat, sandblast, or pretty much any other post treatment on its own.

** Concerning not being able to use 3d printing for mass manufacturing: That is, assuming 3d printing as we think of it today, printing a voxel at a time. However, if you made a custom programmable 3d *molder*, where it forms a cavity of a programmable shape, that could be a different story - then you're approaching true mass production potential. Custom programmable stamping tools and other manufacturing processes could also be developed.

A lot of the slashdot crowd still thinks of 3d printers in terms of Makerbots and the like, the low end consumer-level home 3d printers. They really have no clue what professional level hardware can achieve. They'd be singing a different tune had they ever ordered 3d-printed parts from a professional 3d printing service.

Germany was spending far more on their military during that time than Britain was. If Britain and France had stepped in earlier, Germany would have been totally unprepared and the war would have ended quickly. Not to mention all of the horrors of the Holocaust that would have been prevented.

If Britain and France had managed to delay the war to "prepare" even more, say a few years, the Luftwaffe would have been dominated by jets, German ballistic missiles would have been longer range and more precise, and they might even have become a nuclear power. I really don't think this is the analogy you're looking for.

By now would be surprised if they don't have at least a couple Taepodong 2s that have at least a fair chance of a successful flight. They're not impressive as far as ICBMs go, but they are ICBMs.

Propaganda campaign by who? I think Singer needs to check his haughtiness at the door:

the ability to steal gossipy emails from a not-so-great protected computer network is not the same thing as being able to carry out physical, 9/11-style attacks in 18,000 locations simultaneously. I can't believe I'm saying this. I can't believe I have to say this."

Except, of course, for the fact that the prime suspect is the hand-picked hacker squad of the Hollywood-obsessed leader of a nuclear armed state with ICBMs, whose family's Hollywood obsession has gone to such extremes in the past as kidnapping filmmakers and forcing at them at gunpoint to make movies for them. I can't believe I'm saying this. I can't believe I have to say this.

Well, at least Russians won't freeze to death this winter. They can use wheelbarrows full of rubles to insulate their homes. ;)

That's not all that different from how he got started with Tesla. He had no intention of starting a car company (he already had SpaceX), he just wanted AC Propulsion to build him a copy of their t-zero - but they had no interest, even for a small fortune. But then they pointed him to this guy named Martin Eberhard who had this wild idea to commercialize the t-zero's tech base on a Lotus Elise body and was looking for funding... and thus Tesla was born.

g++ supports it with __restrict__. And if you're writing high performance code but not having support for the features of modern compilers, you're an idiot. In appropriate situations, the performance difference for using restrict or not is huge. Array-heavy tasks like image processing often get a 2-fold or more benefit with using restrict. There's very few places in the coding word where a single keyword can raise your performance that much.

And examples of these which could plausibly be on Titan are....?

There's not much in nature that's that light.

So you think massive yachts, ridiculous-priced art/jewelry purchases, palatial estates, gold-plated toilets and the like are a better use of money?

Trust me, I'd have a LOT more fun with a giant rocket than I would with a gold toilet.

I'll begin by stating that I I don't support such a mission, as I prefer robotic exploration. But this proposal isn't as extreme as it may sound - it's probably a heck of a lot easier than landing on a planet and taking off. It's only 640 m/s from earth escape to Venus (3/5ths that of Mars). Transit time is less and launch windows a lot more frequent. Venus offers very easy aerocapture. You don't have to deal with the randomness of the surface - your "landing" is a lot more forgiving. Your habitat is probably simpler, not having to deal with a surface (although there's a few potential complications that need to be studied, such as storms, and I don know the radiation level at the desired altitude). Keeping it aloft is easy - even normal earth air is a lifting gas on Venus. Solar energy arriving at Venus is double that of Earth. Nearly earth's gravity eliminates a lot of the uncertanties about skeletal and muscular wasting.

One of the neat things is that a person could potentially step outside without any sort of special suit, just an oxygen mask. It's a "maybe", though, as there's a few complicating factors. It's 37C (100F) at the same sort of heights that it's about 600mb; for US analogies, it's Phoenix temperatures at Mount Whitney air pressures (lower or higher for both, depending on your exact altitude - you can choose). So it's not a perfect match - but probably tolerable. But there's two potential complicating gases: SO2/sulfuric acid and carbon monoxide. Breathing them is right out, but even long-term (hours at a time) skin exposure might be problematic at the given concentrations; it's not certain whether at these altitudes they'd be prohibitive. They would however make eye protection a must at the very least, the eyes are more sensitive to both CO and SO2 than the skin.

Manned or not, the main advantage of a Venus blimp would be the lower altitude it would provide to scientific equipment versus satellites. So you'll get a lot more information on the atmosphere, which could help answer questions about Venus's evolution (and how other worlds in other systems might be). You'll get higher resolution radar imaging of the surface. You simplify to some extent sample return missions from the surface, as each sample collection doesn't have to be a self contained return mission. Etc.

One thing on Venus I'd love to see studied more is the super-reflective radar surfaces. It's now believed to be due to a "galena snow", snow made of shiny, electrically conductive lead sulfide. I'd really love to know more about the surface minerology of Venus in general.