Lateral flow immunoassays (LFIA) are widely used worldwide for the detection of different analytes because they combine multiple advantages such as low production cost, simplicity, and portability, which allows biomarkers detection without requiring infrastructure or highly trained personnel. Here we propose to provide solutions to the manufacturing process of LFIA at laboratory-scale, particularly to the controlled and active dispensing of the reagents in the form the Test Lines (TL) and the Control Lines (CL). To accomplish this task, we adapted a 3D printer to also control Syringe Pumps (SP), since the proposed adaptation of a 3D printer is easy, free and many laboratories already have it in their infrastructure. In turn, the standard function of the 3D printer can be easily restored by disconnecting the SPs and reconnecting the extruder. Additionally, the unified control of the 3D printer enables dual, active, regulable and simultaneous dispensing, four features that are typically found only in certain high-cost commercial equipment. With the proposed setup, the challenge of dispensing simultaneously at least 2 lines (CL and TL) with SPs controlled by a 3D printer was addressed, including regulation in the width of dispensed lines within experimental limits. Also, the construction of a LFIA for the detection of leptospirosis is shown as a practical example of automatized reagent dispensing.