Markforged X7 3D printing is a kind of additive manufacturing that can be used to rapidly fabricate components of composite material with highly customizable geometries, using a laye by-layer fabrication process. The base material used to print the components is called Onyx: a polyamide loaded with short carbon fibers. The base material can be reinforced by adding continuous reinforcing fibers: carbon, Kevlar, Glass, High Strength/ High Temp glass. These composite materials can match the strength of many metals, but at much lighter weight. In particular, the addition of carbon fibres to plastic resins is becoming a widely used strategy to enhance the mechanical properties of 3D printed parts. The double extrusion, Continuous Fibre Fabrication (CFF) and Fused Filament Fabrication (FFF), allows to create composite parts incredibly strong and versatile.