Unlike traditional manufacturing, which involves injecting material into a pre-formed mold or removing material from base material objects, 3D printing starts with a virtual 3D model that is transformed into solid form one layer at a time. Each layer is built on top of the layer before, creating a solid form representing the virtual 3D model in all of its complexity and detail without requiring additional forms of machining and treatment necessary in traditional forms of manufacturing.

When your 3D printer's hot-end gets blocked or your extruder's filament drive fails, the warning signs are usually obvious. The stream of plastic starts to lessen and then stops; the printer keeps trying to print but extrudes layer after layer of nothing.The first things to do are stop the printer and ensure that the heater block on the hot-end is still at the expected temperature.

It is possible to capture existing objects into the computer so they can be modified or simply re-created using a 3D printer. This is particularly useful in the case of artwork or other unique formations that could not otherwise be designed easily in a computer model.The Glen Rose dinosaur track, for example, came from a laser scan of the original fossilized impression, which was used to create an electronic copy of the track that can be shared without risk to the original.

Here's an important tip for using 3D printing extruders: Use fans. Use a small fan to keep the cold-end insulator of your hot-end below the glass-transition point of your plastic. When you start experimenting with printing ultratiny objects with fine details or printing objects at great speed, you quickly discover an interesting problem in 3D-printing thermoplastic materials: controlling layer temperature.

For thermoplastic printing on a 3D printer, it's a good idea to have two or more extruders of the same type, but with different nozzle sizes and maybe a choice of 3mm or 1.75mm filament. Some materials — especially experimental materials — tend to come in 3mm and less often in 1.75mm. Depending on the manufacturer, 3mm filament may cost less than 1.

Here are some tips to keep your extruder and 3D printer happy. Keeping your extruder in tip-top condition is important, because the extruder is the device that takes the most wear and tear in your 3D printer. Follow this advice to make your 3D printing go smoothly, prevent failed prints, and keep your new 3D printer in action: Check the accuracy of your software and firmware.

Any standard 3D printer's single-grip extruder also needs an idler wheel to push the filament into the teeth of the drive wheel. An idler wheel usually is a round bearing pushed by a spring or a rubber bushing.The following figure shows an idler bearing/wheel fitted to a printed lever; the spring on the left causes the bearing on the right of the image to be pushed into the drive wheel (middle), gripping the filament tightly.

The extruder is one of the most important parts of a 3D printer, so the quality and reliability of parts are critical. The filament drive mechanism almost always takes the form of a round bolt or rod with concave teeth that grip around the plastic. Typical filament drives used in thermoplastic extruders. Filament drive mechanisms can be machined in a variety of ways.

A RepRap development goal for home 3D printing is to print objects in many colors and even mix, on demand, the color of your choice from a set five or six master materials. Full-color home 3D printing is still a little way into the future, but you can use several current methods to brighten your 3D-printed objects.