We present a new hybrid technology for the realization of three-dimensional millimetre-size inductors for low-power (0.1–1 W) applications. Our devices consist of electroplated planar Cu coils, realized within a high-resolution (5 µm) polyimide flex-foil process, and mm-size ferrite magnetic cores, obtained by three-dimensional micropatterning of ferrite wafers using powder blasting microerosion. Our devices range in volume between 10 and 1.5 mm3 and we characterize their inductive and resistive properties as a function of frequency.