The work is dedicated to the study of a spatial system of straight cantilever bars having one common end. The bars have embeddings, and the common end is also considered fixed. Compared to the standard lengths, the bars may have longer or shorter lengths because of the fabrication errors. At the common point of the bars, a system of forces acts, which is reduced to a resultant. The first aspect considered is that of determining the equilibrium position (the position of the common point of the bars). Another aspect studied is that of determining certain geometric and mechanical characteristics of a new bar with known fabrication errors that is added to the system in order to minimize certain (linear or angular) deformations or certain stresses in certain bars. The geometric and mechanical characteristics of the new bar can only be found within certain variation intervals. The problem cannot be solved in the general case except by numerical calculation. A numerical example illustrates the presented theory.