There is provided a build material source container for use in a material management station of a three dimensional, 3D, printer. The source container defines a substantially enclosed space for holding build material and has an aperture for build material ingress and egress. At least part of the build material source container is formed from an electrically conductive material. The conductive material portion of the build material source container is connectable to Earth to discharge static electricity generated within the build material source container.