Crowdsourcing has been widely used in cultural heritage research, but mainly from an institutional perspective. Research into items of material culture often requires the researcher to examine specimens held in private hands. The dispersed nature of such holdings, primarily as collectable and, thus, tradeable objects, requires different techniques for identification and access than that for items held in museum collections. Crowdsourcing data from online discussion groups and online marketplaces, coupled with snowballing, represents a very powerful tool. This paper discusses the relevant parameters and provides a protocol for the systematic compilation of items held in private hands.