While studying my competition I greatly improved their design… there are few rolling jerrycans like waterwheel and Q Drum having a cylindrical shape container rolling on ground. Rolling water on ground requires roll-able ground and rough terrain, muddy ground and steep slop would make the product unable to use but if you can roll it make the shape SPHERE is ideal because sphere have one point contact with the ground reducing the surface friction which result in lower force needed to push the jerry can.