The objective of this study is to present an overview of manufacturing techniques (current under development) that can be used to produce solvent-free polymer membranes. The applicability of various methods is discussed. In particular, a new continuous technique by foam extrusion from the thermoplastic polymer is presented. Open-cell hollow fibers made of polyethersulfone (PES) and polycarbonate (PC) with pore diameters smaller than 10 mm and a homogeneous pore size distribution can be produced. The variability of the pore morphologies and the membrane properties are shown and potential applications for such membranes are described.