Application of the neural networks to the design of optical elements for the THz spectral range allows to obtain unique, counterintuitive phase delay maps, which can redirect the incident radiation into arbitrarily chosen intensity patterns. In this work, the neural network optimization of three structures is presented – a converging lens, a three-focal-spot lens, and a hologram of a square. The structures have been manufactured using the 3D-printing technique and verified experimentally. Proper functioning of such diffractive elements and high compliance with the numerical simulations has been proved. Proposed diffractive elements can be applied to many areas, including wireless telecommunication or imaging.