Harvesting power from walking-related motions can be a sustainable energy source for powering wearables. This paper proposes a shoe insole with a 3D stackable self-supporting structure and energy harvesting capability based on triboelectrification. Initial tests showed that a unit cell of the structure could produce an open-circuit voltage of 164.5 V with a charge density of 2.02 nC/cm2, and the performance can be further improved with a higher force and a structure of multiple cells.