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For deep drawing of sheet metals and converting them to irregular shaped prismatic shells which have been designed before, the initial blanks should be correctly designed. Otherwise, final products will not be sound. The design of the initial optimum blank is, therefore, very important. The initial blank could be designed experimentally or numerically. Numerical methods have very advantages. In this paper by using slip line field theory and geometrical characteristics of die, just
like angles and radii of corners, sides' length and height of draw, a new method for initial blank's design will be presented. Then by using a new applied method, an equarial orthogonal net will be constructed around the die. Using constructed net, metal flow paths and blank's movement contours will be obtained. The punch stroke will then be calculated, using material properties and equarial orthogonal net, during the different stages of drawing. According to the mentioned methods, a package has been written that in a very short time, can predict optimum blank shape, metal flow paths, blank's movement paths and punch load, with appropriate precision.