Haptics, namely the sense of touch, has been playing an important role in medical simulation. However, most medical practitioners, who are best suited to create the training environments, do not have the engineering expertise necessary for programming a haptic environment. We propose a user-friendly interface that allows surgeons to arbitrarily select regions on a 3D model of an organ, similar to “painting-by-numbers”, and tune the haptic properties of each region in an intuitive way. The selected region and tuned haptic properties are recorded in a lookup table in real-time. The proposed user interface is assessed by comparing the haptic effects of a tumor on a virtual liver created by a number of surgeons.