The integration of actuators within disposable lab-on-a-chip devices is a demanding goal that requires reliable mechanisms, systematic fabrication procedures and marginal costs compatible with single-use devices. In this work an affordable 3D printed prototype that offers a compact and modular configuration to integrate actuation in autonomous lab-on-a-chip devices is demonstrated. The proposed concept can handle multiple step preparation protocols, such as the enzyme-linked immunosorbent assay (ELISA) configuration, by integrating reagents, volume metering capabilities with performance comparable to pipettes (e.g. 2.68% error for 5 μL volume), arbitrary dilution ratio support, effective mixing and active control of the sample injection. The chosen architecture is a manifold served by multiple injectors ending in unidirectional valves, which exchange a null dead volume when idle, thus isolating reagents until they are used. Functionalization is modularly provided by a plug-in element, which together with the selection of reagents can easily repurpose the platform to diverse targets, and this work demonstrates the systematic fabrication of 6 injectors/device at a development cost of USD$ 0.55/device. The concept was tested with a commercial ELISA kit for tumor necrosis factor (TNF), a marker for infectious, inflammatory and autoimmune disorders, and its performance satisfactorily compared with the classical microplate implementation.