A method is provided for a plumbing parts supplier to reduce inventory of sink drain assemblies. Drain assemblies for overflow-type sinks have an overflow port, while drain assemblies for vessel sinks do not. Some drain assemblies have open and closed positions, while a grid drain or an umbrella drain does not. A drain assembly may be available in different finishes. Rather than having an inventory of drain assemblies for all possible applications, kits are provided that allow an end-user to assemble one of two or more drain assemblies. One kit includes a drain assembly for an overflow-type sink and a sleeve that fits in the drain assembly and covers an overflow port. Other kits include a drain assembly with a push-type open-close mechanism and means for keeping the drain assembly in the open position. Another kit includes a push-button drain assembly with an overflow port, means for converting it an umbrella drain and a sleeve for covering the overflow port.