Automated D-Cell Battery Dropper

I already have the electrical trigger sorted—I can close a relay on command—so what I need now is the physical device that releases a single D-cell (originally horizontally oriented), guides it down a... (Budget: $30 - $250 USD, Jobs: 3D Design, 3D Modelling, 3D Printing, CAD/CAM, Electronics, Mechanical Engineering, Product Design, Prototyping)