Combining metal and semiconducting components in the core of a glass-clad fibre brings new breadth to the range of structures that can be fabricated using localized thermal gradients. Both axial and lateral structuring of fibres drawn withm ultiple components is demonstrated, as well as the introduction, segregation and chemical reaction of metal components within an initially pure silicon core. Gold and tin longitudinal electrodes fabrication, segregation of GaSb and Si in an initially inhomogeneous fiber into parallel axial layers and Al doping of a GaSb core were demonstrated. Gold was introduced into Si fibers to purify the core or weld an exposed core to a Si wafer. Ga and Sb introduced from opposite ends of a silicon fibre reacted to form III-V GaSb within the Group IV Si host, as confirmed by structural and chemical analysis and room temperature photoluminescence.