A Langmuir-Blodgett (LB) trough has been developed from the ’diamond design’ previously reported, by fixing two points of the diamond to facilitate a modular construction which could also be conveniently adapted for alternating-layer and Montal-Mueller studies. With biomolecular applications in mind, the trough was deliberately made small; barriers can vary the surface area between 115 cm2 and 17.5 cm2 with a low subphase volume of about 550 cm3. The surface flow is channelled by shoulders; this produces near-normal flow at an LB substrate, and yields high quality films for both low molecular mass materials and appropriate polymers with a wide range of surface viscosities.