QTray bioassay tray supports large-scale culture and screening of bacterial and yeast libraries, and has been redeveloped with a focus on both convenience and facilitation of rapid workload management. Formation of condensation, following either media pouring or a change in temperature from storage, often is a rate-determining step in processing samples. To expedite its removal, the QTray now features vents beneath its lid. Also, level fill lines around the tray base facilitate fast and accurate media pouring without prior measurement of media volume. These trays provide a large surface area, are simple to use, and are automation-compatible. Where regional picking is required, a unique 48-well divider fits in the tray to provide discrete regions of 35 mm × 30 mm. Using just two QTrays, this gives a capacity equivalent to 96 separate Petri dishes and offers an economical approach to procedures where stringent selection of a subset of transformed cells is required, such as protein expression.