The thumb can be considered the most important finger of the human hand for handling objects. Compared to the other fingers, the thumb has much greater range of motion. This allows the thumb to flexibly place contacts and exert a variety of forces on an object held in the hand. The thumb design of the latest RBO Hand 3 (RH3) allows our hand to behave more skillfully than prior versions. In this work, you will investitage a two-thumb design of the RH3 (Puhlmann et al.), with the goal of being able to flexibly provide contacts to improve manipulation capabilities in the hand.