New to the world of prototyping is an exciting new technology.  What you basically have is a print head, like on an ink jet printer. Except that this print head squirts ABS resin in tiny drops.  The Dimension SST has two print heads, one for the ABS and another for a water soluble material that is there to hold the ABS resin rigid till it hardens.  This technology is being referred to as a 3D Rapid Prototyping Printer.  

It really is amazing what it can do. The entire machines is stand alone and about the 
size and shape of a medium counter top refrigerator.  

This is the table where the process takes place. There is a tray of black plastic that the 
machines builds a base out of the water soluble support material and then starts the 
build using the ABS material.
 

Here is a part, connecting rod and if you look closely at the surface between the build plate
and the part, there is a black shadow, this is the support material. 

The real magic is the final products. 

This is a fully formed object with hollows and internal structures.  Note the hinge pin and hinge is complete
and formed all at the same time.  The water soluble material is half a millimeter thick between the barrel and 
the pin of the hinge.  

Inside there are two compartments with snap lock lids. In the previous image you can see the
finger hole where you pry the lids open, this is the only access point for the hot water bath
to enter to dissolve the water soluble support material.  If you look closely at this view, the right
side in the compartment you can see some of the residue left over that was not completely
dissolved.  Pretty darn amazing. 

Next is a hole punch head for a paper puncher, this too was fully formed as a working part. 
Once again you can see that there is internal structure and a slide fit of the two parts. 
  
If you look closely at this image and other you can see a texture. This is actually the scan lines of the print head. 

The third object is a cube with hole on each side and a ball inside which is larger than the holes.  A toy and 
example of what this machine can do this is beyond the capabilities of normal machining. 

So how good is this stuff, well it is ABS which is a pretty darn good material.  ABS is what 
most of your plastic car parts are made of, from the mirror covers to dash board and door
panels.  It is a rigid material, weather resistance and can be thermal formed. 

Here are a couple more items.  One is a wheel designed in Solid Works as a tutorial project.
This is the prototype, which then will be sent to MasterCAM software to CNC machine a
mold for injection molding the part.  The mold material is Corian. 

I sat in on the design phase, picking number of spokes, dimensions, filets, hub diameter, etc.
Once again you see the scan lines when the resin was laid down.  This is a low resolution
build so the scan lines, material is much coarser than the white pieces above. 
The diameter of this wheel is 1 3/8", as a reference to size. 

Here is a VIDEO of the Techno 4896, 4' x 8' flat bed CNC router producing one half of the wheel 
mold out of CORIAN. 

Greg Meyers also pulled from his files a piston for the steam engine he built and prototyped it. 

Not to leave well enough alone I wanted to see how strong this material was. So with a 
pair of pliers we preceded to bend and twist the material till failure.
 

As you can see it broke along fracture lines. You can also more clearly see how the machine
lays down resin to build and object.  The skin is one layer then the fill is layer upon layer.

This is very exciting and fascinated stuff.  This machine turns out a pretty nice part. Even in this small size,
the thickness of the rim this wheel is 0.125".  The fracture outside edge measures .015"   This is a prototyping
level of resolution and these parts were never meant to be of production quality. 

NOTE: the machine has the ability to specify resolution and density. 
This wheel is low density which means that the outside is dense but
the inside is just enough material to hold shape.  The white pieces above were
specified as more dense or solid shapes, so the entire structure is more solid. 
I asked if the level of resolution, dot size, drop size could be specified and the person
I was speaking with was not sure.  GOTO the website: www.dimensionprinting.com
they have an excellent promo video that shows a great deal about the machine.

I read in one of their promotion pieces about a company that was called upon to
make a camera gun site for the Army's Abram tank, the parts run was only forty pieces
and they successfully produced a part that met Army standards and testing,
so this technology is capable of producing a working part. It is not just for prototyping.

Price is around $35k for the SST which uses the bath to dissolve the support material
and about $6k less for the BST which is designed to have the parts picked away from
the support material.  The one I saw in operation was the SST and I think the purchaser
was right about NOT wanting to spend a lot of time with a dental pick trying to clear all the
support material from a complicated part.