An appropriate machine prototype was developed and evaluated for densification of rice straw with molasses into animal feed blocks, to enable efficient utilization of rice straw, and to improve the feed bulk handling, transportation, and storage properties. The machine prototype involved two main parts namely: hydraulic press and compactor parts (mold, rammer and free base). The feed raw material samples were densified under the effects of four pressure levels (24.52, 34.32, 44.13 and 53.94MPa), two geometrical mold shapes (cube and cuboid), four molasses content levels (4, 6, 8 and 10%), and three moisture content levels (about 10.32, 13.41 and 16.58%, w.b.) by a piston-mold process. The properties of the densified animal feed blocks were illustrated with respect to bulk density, densification degree, resiliency, durability and stiffness. Also the performance of densification machine prototype was evaluated in terms of its productivity and cost unit. Results indicated that, the optimum conditions for producing good quality densified feed blocks, were obtained by applying hydraulic pressure of 53.94MPa, molasses content of 10% and straw moisture content of 16.58%. As densification process was carried out respectively in cube and cuboid molds under these variable levels, the produced feed blocks, exhibited respectively: bulk densities of 659.87 and 632.04kg/m3, densification degrees of 281.41 and 265.32% and resiliency indicates of 8.35 and 10.03%. The results also indicated that, the highest durability values of 99.27 and 96.92% were respectively obtained for both densified cube and cuboid blocks at moisture content of 10.32%, compression pressure of 53.94MPa and molasses content of 10%. At the same mentioned densification conditions, the highest block stiffness values (385.22 and 380.86N), were respectively obtained for both densified cube and cuboid blocks. For choosing a proper geometrical mold shape, the results reveled that the densified cube blocks were high stability compressed blocks compared to cuboid blocks. The average productivity of the investigated feed block formation equipments was 60 feed block/h (45kg/h), while, the machinery unit cost was about 8.144LE/h (0.18097LE/kg).