Galileo's telescope
Experience the world as Galileo discovered it. Grind a 2 1/4" lens like Galileo did and build a telescope out of every day materials.
Using off the shelf plumbing parts the tubing is adapted to hold the eye piece and slide in and out to focus.
The 2 1/4 inch lens is held in place by the coupling. The masking tape is there to hold the coupling in place so the lens can be removed if necessary.