These plans are for a homemade telescope that will be cheap to build.
THE 6-inch f/8 Newtonian reflecting telescope is probably the most popular star gazing instrument in use by amateur astronomers. This is easily understood when we examine the instrument in more detail.
The "6-inch" refers to the diameter of the objective or main mirror of the telescope and thus affects the diameter of the main telescope tube. The name "Newtonian" refers to the over-all design of this type of reflecting telescope in which rays from the objective or main mirror are focused onto a smaller mirror known as the "diagonal."
It is enough to say that the Newtonian design is simply the most practical and least expensive for nonprofessional instruments. The word "reflecting," of course, distinguishes this scope from a refractor in which the light rays are "bent" through and focused behind a lens instead of being "bounced" away from and focused in front of a mirror.
It's about the largest telescope you can comfortably carry. Much larger reflectors—those over 8 inches in mirror diameter—require the construction of a permanent observatory. Another obvious reason for the popularity of Newtonian reflectors this size or smaller is price.