Different printers use different printing techniques. Consumer 3D printers generally use one of two main approaches.
How 3D printers work - FFM (fused filament manufacturing, also referred to as filament deposition manufacturing or fused filament deposition) printers use a moving print head to build up layers of melted plastic filament in the shape of the object.
SLA (stereolithography) printers solidify resin using an ultraviolet laser (some models use Digital Light Processing projectors, but those tend to be less precise). SLA printers are generally more costly, but they are capable of more accurate and detailed models because of the resolution and precision of the laser.
FFM printers can typically feed a multitude of materials through their extruders. Common choices include ABS, an inexpensive, petroleum-based sturdy and recyclable material, and PLA (Polylactic Acid), a tough, biodegradable material that’s both heat malleable and paintable, but it’s also more difficult to glue than is ABS. These materials often come in a range of colors, but since most printers have just a single print head, you’ll generally print your entire object in a single color.
SLA printers have more limited choices in both available materials and available colors. The material choices will depend upon whether the printer uses the ultraviolet laser or a DLP projector. The resins materials can be be either rigid or flexible, and are more expensive than the plastic filaments used in FFM printing.