We used 1/4" copper tubing and fittings, which gave us strong, smoothly curved components to work with. We bought some of the hollow copper balls, and some we made ourselves. The Leyden jars are not fixed, and can be charged, and picked up to carry the charge over to other equipment. The other special feature is the brass upholstery nails in the sectors. The reason for those is that the brushes on the neutralizing bars must make contact with the sectors on the disk, though the brushes on the high-voltage pickoff brushes do not need to touch the sectors. Brushes touching the copper foil eventually scratch the plexiglass disks, and nick the edges of the foil. In this design, the neutralizing brushes touch only the raised uphostery nails, not the foil, and the HV brushes are positioned opposite the flat copper foil sections.