In this research, we have developed a cost-effective and simple strategy to fabricate sizesorting PDMS microfluidic devices using consumer 3D printers and a standard replica molding technique. The innovative aspect of this microfluidic is that it can size sort particles down to 25 µm on the Z axis because of its internal staircase structure. While fabricating features of 25 µm in the XY plane is difficult and time-consuming, making them along the Z axis is simple and fast. We proved the usefulness of this simple microfluidic device by filtering and sizesorting parasite eggs, microplastics, and zooplankton. This device, coupled with a cheap microscope, can be used, for example, in citizen science projects, to detect zooplankton in different parts of the world, while at the same time involving citizens in scientific projects.