The problems of geometric modeling of closed composite parametric Bezier curves are discussed in this paper. The main attention is given to control of the constructed curves shape without usage of Bezier points which are already computed according to continuity conditions. The local modification of C2-continuous parametric curves with preserving smoothness conditions is possible due to a method of compound functions, which was for the first time offered by Coons S.A. Some problems of designing of so-called surfaces of dependent cross-sections also are considered in this paper. Some examples of the plots and pictures are resulted. The discussed techniques are used at training of the students in the Moscow State Aviation Institute.