Sometime ago I discovered povray, a ray tracing program which generates stunning three-dimensional graphics. I used it to draw nanostructures and in particular nanotubes in different configurations, hereafter the plots and the corresponding scripts:

From left to right:
1) illuminated nanotube, STM_tips.pov
2) gated nanotube, gated_tube.pov
3) nanotube and STM tip, light_tube.pov