Stereolithography is horizontal, one layer at a time, and uses photopolymerization (that's Formlabs). (Also Digital Light Processing is close but distinct: https://formlabs.com/blog/3d-printing-technology-comparison-...)
Continuous Liquid Interface Production (CLIP) also uses photopolymerization, but pulls the object from a liquid bath and uses a buffer zone. Still horizontal slices. The upshot is it's much faster. (Carbon 3D is the company behind this.)
The method in the article uses photopolymerization to solidify the object as a set of slices, but the slices are not horizontal.
The big drawback to photopolymerization is it only works on certain resins which can often have undesirable mechanical properties (high elasticity or brittlness, for e.g.) Potentially this method could be a way forward in that respect, because you might be able to put structural materials in the resin solution and end up with a composite. It seems easier to do this way than with CLIP or SLA/DLP, but I'm purely speculating.
- Fused deposition modeling (FDM): the typical plastic filament-extruding hobbyist printer. Low resolution, but fast and creates very strong parts in one of wide varieties of well-known engineering materials. Tricks (e.g., two extruders) can give limited multiple colors or materials.
- Selective laser sintering (SLS): a laser melts a pattern into one layer of powder at a time. Can make even stronger parts than FDM by using nylon, titanium, etc. Very common in industry, but usually too expensive for hobbyists. These are the printers used to make rocket engines.
- Stereolithography (SLA) as explained above works like SLS but cures liquid resin with light instead of melting powder. Has many subvarieties. Advantage is scary high resolution (certain engineering choices give 160 nm (!) feature size ), but at the cost of relatively limited material choices because materials need to be liquid UV curable (though Form 2 has a good library now ) and definitely no multi-material or color parts. I'd consider this new 3D rotation printer a variety of SLA. [Edit: for clarity, I lumped CLIP and DLP here with SLA]
- Inkjet-based printers: these are the _really_ cool ones. Objet makes a printer  that uses inkjet heads to deposit multiple colors and materials in the same part layer-by-layer (kind of combining FDM and SLA). Upside is multiple colors and materials and resolution (e.g., Lego uses these for prototyping), downside is ridiculous price and low speed. Other printers like HP's and Z Corp's combine inkjet heads with SLS powder instead.
There are also a few weirder ones, e.g., paper layering, but I don't think they're widely used.
There is one application of composites that's extremely disruptive though: producing ceramic parts. It has been found that you can mix in ceramic powder with the resin fire it in an oven to make very detailed ceramic parts. Structural properties aren't necessarily that good, but that's ok because it's good enough to make very complex and detailed investment casting molds. Investment casting molds for making single crystalline jet turbine blades are very complex and require a very complicated process to produce, with this process they can be made in one step. That's a huge disruption right there and investment casting is a pretty general process. The detail produced by this process is so high that the the triangulation of STL became a problem and a special file format developed for fax machines had to be used to represent all the slices.
* rotating the projector instead of the tube to reduce distortion from resin movement (like in a CT scanner)
* speeding this up, using higher energies to compensate
* using multiple projectors at e.g. 90degree angles, to reduce time (and thus probably distortions through movement in the resin)
* using other wavelengths with e.g. more energy, or just better absorption properties for the resin
or are there any obvious problems with that?
This is kinda wacky. Rather than a conceptually simple layer by layer approach, this has this funky convolution. they're getting it for free with the simple rotation. You can kinda see how bulbous that airplane model is, because some finer details get 'overexposed'. i bet, if they could rotate 10x around 1 axis and 1x around another axis, that tumble would sharpen up some of those edges, since you wouldn't be baking the same adjacent space so much.
Think about a 6 sided pencil. if you just rotate around the main axis, it's probably going to look pretty round without the crisp hexagon sides. but if you can also rotate around a minor axis, you could also project just the hexagon shape for a while and still preserve the cone of the tip of the pencil since most of the solidification came from the sides.
There's an opportunity for deep optimization there. Seems tricky. but pretty cool.
it's almost like pca. what projection (or series of projections) maximize hitting the target, and minimize the overbaking, all while taking into account the characteristics of the resin. maybe you can let it cool for a bit, and have more freedom to expose without hardening.
also, not a replicator. this is just one _fabulously special_ super material you mess with, not metal and plastic and cloth and fur and chitin and whatever.
Their problem is that the projector they are using is projecting a 2D plane.
It would be a different story if it was a circular projector (think of a LED strip).
It has to be then rotated only along a single axis.
Turning the projector circle physically can possibly add additional precision.
Magnetic fields can be used to keep the container sphere in place.
I am now going to take the screenshot of this conversation and send it to my self in a registered mail.
Yes, they can be fast.
They should fix their headlines.
This works as the article says, like a CT scanner in reverse. The resin solidifies all at once in the middle. It's very different.
if there's an energy threshold to overcome to cause hardening, and if you can arrange for 2 sources to just barely exceed that threshold, then you could have very crisp prints.
chemistry is statistical though. you can exceed the threshold, but nothing happens because you get unlucky with some fraction of the light. You don't exceed the threshold, but you catch a bad reflection and harden stuff you don't want. and there's probably not a crisp threshold for hardening. it's more likely just time under light.
But i think you're right. two projectors at half power (let's pretend it's linear), with the projections 90 degrees out of phase, i think the print quality would go way way up.
To classify as a ‘replicator’ it needs to be able to mix different materials (metal, plastic) seamlessly in one print as to be able to replicate itself. Not there yet...
I have been wondering if something like that was possible. I've also wondered if something more akin to holography could be used to create a 3D interference pattern in a liquid to create an object. Both seem like they'd be interesting and have limitations.
From the comments here I think some folks don't realize the mathematical details involved in this - they are not projecting a "picture" of the object from each angle going around. Yes, it's an image, but not it's not what you'd expect. It's more akin to an x-ray of the object, and probably with some extra processing beyond that.
EDIT: Looks like I'm wrong. It says the create an image of what the object would look like from each angle. I believe that means their quality is lower than it could be had they actually used more sophisticated methods to create the images.
I'm pretty sure the researchers were using a normal computer projector and not a slide projector. But in my imagination, they printed a bunch of slides, fed them into a carousel projector, and pointed them at an old Smuckers jelly jar full of resin.
This is already happening for jewelry, digital dentistry, and medical applications – you can buy specialized materials for investment casting.
For example, here's our blog post on casting jewelry from resin prints: https://formlabs.com/blog/introducing-castable-wax-resin-jew...
I don't think the fine art sculpture 'industry' is affected at all by the ease of making copies.
I have mentioned this method of 3D printing here previously. Transmitting data to a volume at high speed can be done in many different ways, at any scale, and with a variety of materials.
I hope to someday demonstrate the printing of a 2 story concrete house in an hour using my technique.
Edit: Here's a link to the application on google patents.
Continuously illuminating the entire volume means you also illuminate parts that should stay liquid, but you prevent over-illuminating those parts by illum8nating from a lot of different directions, just as a CT image can see transparent parts of a volume that are hidden by more opaque parts in some views.
Another advantage I see is that this doesn’t need a start-stop motion that lifts the object being constructed by a layer at a time or that raises the surface of the liquid by the thickness of one layer, something that, AFAIK (I don’t followed developments closely, so I may not know much) the traditional printers need because they only can print at the air/liquid surface. Smooth continuous motion is easier to build and faster.
Then it becomes a "fill the cylinder" optimization problem.
Presumably such a video could also easily be computed from CAD models, right?
Generating projections from a model is much easier, because you only need to write the rendering pass and don't have to invert it.
For example, if your image is
The more projections you add at other than orthogonal angles, the more constrained the solutions become.