Carbon nanotubes can be considered as extended carbon "bucky balls" - hollow cylinders of structured carbon atoms (tubular fullerene) which can be capped at the two ends with a hemisphere of a bucky ball. Multi wall and single wall nanotubes are available, with single wall nanotubes exhibiting a regular, near perfect structure when carefully produced. These have a diameter of 0.7-2nm with length being thousands of times the diameter. Read "Inorganic Printed and Thin Film Electronics" www.IDTechEx.com.