We have constructed a customizable, handmade automatic reaction system (Fig. ). This system comprises two main parts: the dispensing system and a rail-operated robotic arm. The dispensing system has a control mechanism with XYZ axes, which determines the spatial coordinates of the micropipette. The device incorporates a universal micropipette, and a servo motor controls the liquid extrusion button. The parts making up the device are the same as those used in open-source general-purpose 3D printers, costing the raw components approximately $1000.