Oil–water emulsions’ pollution and filtration have attracted significant interest in recent decades. Membrane-based unique wettability materials are one such important mechanism for oil–water separation (OWS). The present article considers membrane-based oil–water filtration and proposes an additively manufactured membrane for low-cost and eco-friendly filtration. The surface wettability and the phenomenon mechanism are initially discussed by comparing various wetting models to measure the contact and rolling angles. It is anticipated that the rolling angle has to be less than 10°, and the water contact angle (WCA) has to be greater than 150° to achieve superhydrophobicity. In addition, a few developed methodologies for the surface preparation of membranes to produce a superhydrophobic surface for oil/water filtration are discussed. Since the earlier method was observed to be non-eco-friendly and fabrication processes were costlier, a novel additively manufactured eco-friendly, biodegradable, and biocompatible membrane is proposed with the help of high-resolution 3D printing technology to develop a hierarchical structure for OWS, and its advantages are discussed broadly. Moreover, the problems and drawbacks faced during the preparation and function of the membrane-based material in oil–water filtration and further developments are discussed briefly.