The panel a shows 316 L stainless steel with labelled cracks and a scale bar of 50 micrometres, a stainless steel to C u interface with a labelled 750 micrometre distance, and C 18400 copper with a scale bar of 50 micrometres. Panel b shows two interface micrographs between 1.2709 and C C Z, with X and Z axes and scale bars of 100 micrometres. Panel c shows I n 718 and C u interface micrographs with labels for pore, lack of fusion, pores, and lack of fusion, and scale bars of 50 micrometres and 20 micrometres. Panel d shows a micrograph labelled layer top, fused zone, transition zone, sintered zone, layer bottom, partially melted particle, melted composite, unmelted particle, origin, and crack, with a scale bar of 10 micrometres. Panel e shows direct bonding, remelting, and F G M samples with surface views at 5 millimetres and interface views of C u A and T i A at 100 micrometres, including labels for T i A residue and C u A-T i A. Panel f shows two micrographs labelled C u 10 S n, A g 7.5 C u, diffusion zone, cracks, pores, and build direction, with scale bars of 10 micrometres.Microstructural summary of potential alloy systems to be used to integrate the electrical and thermal conductivity functionality: (a) SEM and EDS images of the 316 L-C18400 steel-copper pair, highlighting their diffusion width (Liu et al., 2014), (b) Microscopic images of the tool steel 1.2709 and copper alloy 2.1293 (CCZ) pair, illustrating the effect of their positioning (Anstaett, 2017), (c) SEM image of the In718 and pure copper pair, indicating some gas pores and lack of fusion (Marques et al., 2022), (d) Microstructure of the Invar36-Cu10Sn pair, here 75 vol% Invar36/25 vol% Cu10Sn, with relatively high number of defects at the interface (Wei et al., 2021), (e) Direct bonding, remelting and gradient of Ti6Al4V-Cu10Sn pair demonstrating the effect of melting on the microstructure at the interface (Wei et al., 2022), (f) Microstructure of the AgCu7.5 and CuSn10 pair, showing the impact of different alloy positioning (Chen et al., 2023)