I remember seeing a web page describing a process that deposited (sprayed?)
material (plastic?) to build up a CAD design so that in the end you have a
3-D prototype of your design.
Basically, a CNC machine that adds material, not takes it away.
Can someone point me to a web reference of this type of machine?
There are MANY different such machines, and they produce imperfect
parts with different characteristics.
Basic methods are--
SLA - stereolithography, where a laser polymerizes a liquid and
it emerges from a bath of liquid like the creature from the
FDM - fused deposition modelling- sort of an automated glue gun
lays down layers. Eg. Stratsys.
LOM - laminated object manufacturing- a roll of plastic is cut
with an automated knife to create layers of the end product
SLS - Selective laser sintering (of powder). This has been combined
with inkjet color printing to produce colorful 3-D object.
Metal powder is possible.
Google for "Rapid Prototyping" and you'll find more info, machines,
service bureaus etc.
Part finish and material bulk characteristics are rather inferior to
solid material in every sense (strength, porosity etc.) and it's
possible to make structures that are not machinable and not
injection moldable (eg. with complex internal voids etc.).
If you don't mind doing a bit of work afterward (polishing, drilling,
filing, painting etc) you can get a fairly good idea of what an
injection molded part will look like before spending the money for a
mold-- even demonstrate functional prototypes at trade shows etc.
Ideal for 'industrial engineers' interested in cool sculptured shapes
I'm currently using several different methods (through service
bureaus) to create small quantities of plastic and metal parts for
high tech applications. I do the modelling in Solidworks, output an
STL file, send it off, and parts arrive by courier in a bit.
You often don't need to go through the finishing steps if all you want to
do is fit checks or ergonomic studies.
I've seen the FDM stuff done in wax, and thought it'd be great way to do
one-off metal parts if you could just use it as the wax for investment
At the other end of the spectrum from DIY home stereolithography,
Space explorers have yet to get their hands on the replicator of "Star Trek" to
create anything they might require. But NASA has developed a technology that
could enable lunar colonists to carry out on-site manufacturing on the moon, or
allow future astronauts to create critical spare parts during the long trip to
The method, called electron beam freeform fabrication (EBF3), uses an electron
beam to melt metals and build objects layer by layer. Such an approach already
promises to cut manufacturing costs for the aerospace industry, and could
pioneer development of new materials. It has also thrilled astronauts on the
International Space Station by dangling the possibility of designing new tools
or objects, researchers said.