This invention provides capacity altering devices that facilitate the processing of samples whose volume exceeds the capacity of external sample processing regions (e.g., sample tubes or wells). The invention also provides holders that can be used with such devices, e.g., to allow centrifugation of the devices and/or to minimize handling of the external processing regions. Methods of processing samples, particularly samples whose volume exceeds the capacity of the external processing regions, and methods of collecting compounds in external processing regions are another feature of the invention.