The aim of this paper is an experimental determination of the most efficient tool trajectories and tool shapes from energy consumption point of view, for heavy machines tools during the filling process. Laboratory tests were performed under plane strain conditions on a constant slope made of cohesive soil, using various model tools. The most efficient tool trajectories were searched, from energy usage point of view, to find a method of excavating an assumed amount of soil; in a single tool pass. As the experiments were performed under the plain strain conditions for simplicity of assembling the photographic documentation, the influence of sidewalls was neglected in this study. The experimental stand, modeling cohesive soil and the method of slope preparation are also briefly presented. The first group of tests was carried out using various curvilinear and piece-wise linear trajectories. The two-staged piece-wise trajectory, consisting of the horizontal movement of the tool and its withdraw along the straight line was found to be the energetically most efficient. In the second group of tests this two-staged trajectory was carefully investigated and the influence of the inclination of the withdraw trajectory was studied and the optimal inclination was established. In the third set of tests various shapes of the model tools were used to investigate the influence of the rear wall position and the optimal shape was identified. It was found, that using, in the model laboratory tests, optimal trajectories and tool shapes one can save over 50% of tool filling energy.