Since transparencies typically are thin, smooth sheets of acetate film, they have very different characteristics than paper. The best way to write on a transparency is with a wet-erase marker.

For the dielectric he is using acetate film. This is the material from which overhead transparency sheets are made. He stuck with aluminum foil for the two plates.

This is where overhead projectors go to die at the University of Colorado. Squiggly math equations can still be seen scrawled in blue and green erasable ink across transparency film, ...

Transparency paper or film is a type of thin plastic sheet. Photocopy or print on this paper to produce clear sheets for presentation booklets or transparencies for use on an overhead projector ...

This is where overhead projectors go to die at the University of Colorado. Squiggly math equations can still be seen scrawled in blue and green erasable ink across transparency film, ...