The cost and logistics of creating such a learning environment may be staggering. During an actual operation it is difficult, if not impossible, to completely separate out levels of learning objectives. At present, most structured technical skill courses outside the OR make use of inanimate (latex) or animate (porcine or canine) physical models. In addition to the ethical considerations in using animals for training purposes, there are other substantial limitations. Dedicated physical space must be available, especially when using animals. In addition to the cost of the animals and synthetic models, other equipment, such as surgical instruments and supplies, must be available and functional. This may include sutures, scalpels, laparoscopic ports and instruments, and video equipment. Maintaining these resources so that they are available on demand for the learner is generally prohibitively expensive and time-consuming.