This is how you see with the teleidoscope:
This is the finished teleidoscope. You can see the lens here, a simple transparent glass ball.
Step 1: Materials
In addition, you will need a spare piece of mirror (depending on the size of the teleidoscope, around 15x10 cms).
Finally obtain the glass ball. It looks opaque when it is close to you, but at around 20 cms (1 foot) it converges light.
Glasscutter & lubricant (cooking oil)
Glass (three 15x2cm pieces)
Transparent glass ball
Paper or duct tape
In the picture, you can see more materials you may need, such as glue and cardboard tubes.
Step 2: Measuring the teleidoscope
My glass ball is around 2cm, which I measured using a sheet of paper wrapped around it.
This will be the diameter of the teleidoscope, but first we need to cut and arrange the mirrors. As the diameter is 2 cm, we will need to put inside this three mirrors arranged forming a triangular structure, that can be seen in the fourth picture below.