Structural design is another strategic point in developing a vibration protection system with mechanisms of negative and quasi-zero stiffness. Missing this stage of the design and errors in designing the structure of mechanisms predisposed to unstable motion can ruin the development idea. A method of structural design of function-generating mechanisms for such systems is proposed. This includes the type and number synthesis of the mechanisms, making this process less empirical and more reasonable and bringing a great number of new candidates. The atlases of the mechanisms for seat suspensions and bogie secondary suspensions for carbody of high-speed trains are elaborated. The method fundamentals are (a) the function-generating mechanism is to be perfectly structured, that is, with a minimal number of redundant constraints; (b) due to unstable motion and transposition of clearances in kinematic pairs, the mechanism with negative stiffness must not directly join the input and output structural elements of function-generating mechanism to avoid structural indeterminacy; (c) mechanisms with negative stiffness shall be joined to the input structural element, and with no more than two kinematic pairs, one of these two is to be higher; (d) an external damping mechanism can be removed from function-generating mechanisms without degradation of the system performance.