The PiKon Telescope combines the Raspberry Pi, some PVC drain pipe and a few 3d printed parts to become a high power telescope capable of some impressive astrophotography. This video goes over building the thing. A primary problem is that the official design uses a type of PVC pipe easily available in England, with a 5" diameter, that isn't available in the USA. You can order a kit of parts from the fellow in England.
The design is a reflector telescope, meaning that a key component is the Mirror assembly that fits in the back of the tube. At the other end of the tube is a "spider" that holds the PiCamera and handles the focusing.
It uses a regular PiCamera with the focusing lens removed. Focusing is handled by moving the camera assembly back and forth.