A drilldriver includes first and second drive shaft. The trenches formed in the substrate reduce a stiffness of the substrate, which provides less resistance to shear. An epoxy-based material is flowed into the gap between the die, the substrate, and the heat spreader via a through-hole in either the substrate or the heat spreader using a dispense process or a transfer molding process. The present swim fin is equally adaptable for use attached to a swimmer’s forearm. Failures that are causal failure are displayed.