Open-source hardware (OSHW), as low-cost and easy-to-use instrumentations, are particularly suited to the needs of the conservation field. This paper presents two OSHWs developed for the diagnosis of heritage metal artefacts. The DiscoveryMat application allows the qualitative analysis of slightly oxidised metals such as copper and aluminium-based alloys, through the standardized monitoring of the variation of their corrosion potential (Ecorr) with time. The Pleco allows the local identification of corrosion products through linear sweep voltammetry (LSV) plots and this contributes to a better adjustment of conservation treatments on metal artefacts covered with heterogeneous corrosion layers through the selective intervention on some corrosion products and the preservation of others. If the Pleco can already be found in the toolbox of some conservation professionals, the DiscoveryMat application is still in its infancy and needs to be developed in the future as a participatory tool.