The waveform diversity of multiple-input-multiple-output (MIMO) radar systems offers many advantages in comparison to the phased-array counterpart. One of the advantages is that it allows one to design MIMO radar with flexible transmit beampatterns, which has several useful applications. Many researchers have proposed solutions to this problem in the recent decade. However, these designs pay little attention to certain aspects of the performance such as the ripples within the energy focusing section, the attenuation of the sidelobes, the width of the transition band, the angle step-size, and the required number of transmit antennas. In this paper, we first propose several methods that can indirectly or directly control the ripple levels within the energy focusing section and the transition bandwidth. These methods are based on existing problem formulations. More importantly, we reformulate the design as a feasibility problem (FP). Such a formulation enables a more flexible and efficient design that achieves the most preferable beampatterns with the least system cost. Using this formulation, an empirical MIMO radar beampattern formula is obtained. This MIMO radar beampattern formula is similar to Kaiser's formula in conventional finite-impulse-response (FIR) filter design. The performances of the proposed methods and formulations are evaluated via numerical examples.