Polylactide plastic (PLA) prototypes are studied by means of additive technology to determine their strength properties in case of tension along the grain. In this article, testing of PLA and its compound PLA HP was carried out. Mechanical properties (yield limit, Poisson's ratio, Young's modulus) are determined. Analysis of results related to comparison of PLA and PLA HP was realized. Plastic is also studied using microscope for determination of adhesion influence on strength characteristics.