How does FDM differ from other 3D printing methods like SLA or SLS?

Fused Deposition Modelling (FDM) is distinct from other 3D printing methods such as Stereolithography (SLA) and Selective Laser Sintering (SLS) primarily because it employs thermoplastics as the printing material. In FDM, a thermoplastic filament is heated and extruded through a nozzle to build objects layer by layer. This method utilizes a process known as additive layer construction, where successive layers of material are deposited to create the final product.

In contrast, SLA uses a liquid resin that is cured with ultraviolet light, allowing it to solidify in specific areas based on the design, while SLS employs powdered materials that are selectively fused together using a laser. This fundamental difference in materials and processes leads to various characteristics in the final printed objects, such as strength, detail, and finish.

The other choices present characteristics that do not accurately represent the differences between these 3D printing technologies. For instance, FDM does not operate at a lower temperature than SLA or SLS, as it typically requires temperatures around 200°C to 250°C for thermoplastic melting. Additionally, FDM is capable of printing a wide range of sizes, not limited to smaller objects, in comparison to SLA and S