These rental or purchase exhibits are fabricated from a variety of materials, based upon the design and needs of the exhibitor. These exhibits often incorporate hard wall panels to create rooms and separated spaces, stages, large metal structures, display and workstations, and other display components. Custom exhibits cannot normally be set up by the exhibitor without utilizing the services of an on site labour source (show general contractor, or a labour contractor approved through show management). Large companies often buy a custom exhibit to be used at different shows in different countries all over the world – a concept similar to the set of sound and stage equipment that accompanies world famous music groups on their tours around the world. Rules for construction of custom exhibits vary from country to country and even show hall to show hall.