1. Computer Numerical Control
Numerical control (NC) refers to the automation of machine tools that are operated by abstractly programmed commands encoded on a storage medium, as opposed to manually controlled via hand wheels or levers or mechanically automated via cams alone.
In modern CNC systems, end-to-end component design is highly automated using CAD/CAM programs.
The programs produce a computer file that is interpreted to extract the commands needed to operate a particular machine, and then loaded into the CNC machines for production.
Since any particular component might require the use of a number of different tools - drills, saws, etc. - modern machines often combine multiple tools into a single "cell".
In other cases, a number of different machines are used with an external controller and human or robotic operators that move the component from machine to machine. In either case the complex series of steps needed to produce any part is highly automated and produces a part that closely matches the original CAD design.

2. Rapid Prototyping
Rapid prototyping is the automatic construction of physical objects using solid freeform fabrication.
The first techniques for rapid prototyping became available in the late 1980s and were used to produce models and prototype parts.
Today, they are used for a much wider range of applications and are even used to manufacture production quality parts in relatively small numbers.
Rapid prototyping takes virtual designs from computer aided design (CAD) or animation modelling software, transforms them into thin, virtual, horizontal cross-sections and then creates each cross-section in physical space, one after the next until the model is finished

3. Stereolithography
Stereolithography is a common rapid manufacturing and rapid prototyping technology for producing parts with high accuracy and good surface finish. A device that performs stereolithography is called an SLA or Stereolithography Apparatus.
Stereolithography is an additive fabrication process utilizing a vat of liquid UV-curable photopolymer "resin" and a UV laser to build parts a layer at a time.
On each layer, the laser beam traces a part cross-section pattern on the surface of the liquid resin. Exposure to the UV laser light cures, or, solidifies the pattern traced on the resin and adheres it to the layer below.

4. Selective laser sintering
Selective laser sintering is an additive rapid manufacturing technique that uses a high power LASER (for example, a carbon dioxide laser) to fuse small particles of plastic, metal, ceramic, or glass powders into a mass representing a desired 3-dimensional object.
The laser selectively fuses powdered material by scanning cross-sections generated from a 3-D digital description of the part (for example from a CAD file or scan data) on the surface of a powder bed.
After each cross-section is scanned, the powder bed is lowered by one layer thickness, a new layer of material is applied on top, and the process is repeated until the part is completed

5. Fused Deposition modelling
Fused deposition modelling, which is often referred to by its initials FDM, is a type of additive fabrication or (sometimes called rapid prototyping / rapid manufacturing (RP or RM)) technology commonly used within engineering design.
FDM works on an "additive" principle by laying down material in layers.
A plastic filament or metal wire is unwound from a coil and supplies material to an extrusion nozzle which can turn on and off the flow.
The nozzle is heated to melt the material and can be moved in both horizontal and vertical directions by a numerically controlled mechanism, directly controlled by a computer-aided manufacturing (CAM) software package.
The model or part is produced by extruding small beads of thermoplastic material to form layers as the material hardens immediately after extrusion from the nozzle
Fused deposition modelking: 1 - nozzle ejecting molten plastic,
2 - deposited material (modelled part),
3 - controlled movable table

6. 3D Printing
3D printing is a unique form of printing that is related to traditional rapid prototyping technology.
A three dimensional object is created by layering and connecting successive cross sections of material.
3D Printers are generally faster, more affordable and easier to use than other additive fabrication technologies.
While prototyping dominates current uses, 3D printing offers tremendous potential for retail consumer uses

7. Laminated Object Manufacturing
This is considered to be obsolete but is still widely used in industry. The model is built up in layers using a foil with an adhesive backing. Each layer of foil is pressed to the next using a heated roller and is then cut but the laser.
Step by step:
The process is performed as follows:
Sheet is adhered to a substrate with a heated roller.
Laser traces desired dimensions of prototype.
Laser cross hatches non-part area to facilitate waste removal.
Platform with completed layer moves down out of the way.
Fresh sheet of material is rolled into position.
Platform moves up into position to receive next layer.
The process is repeated