An Aristotle telescope is simply created with two plus lenses. You line them up such that their focal points coincide. The length of the telescope tube needs to be the combined focal lengths for your two lenses. For example, a 3-diopter lens and a 4-diopter lens would require a 33cm + 25cm = 58 cm tube length. (Remember that the resulting image from an Aristotle telescope is inverted, which makes sense if you look at a ray tracing).
