One of the things I can observe with my 80mm refracting telescope is the Sun. I use a white light filter for this (the shiny metallic film in the picture below) which rejects something in the region of 99.99% of the incoming light. The problem in my observatory is that the refractor isn't alone, it is mounted on a dual mount bar with a much larger (200mm) reflecting telescope. Unfortunately I lost the dust cover for the reflector some years ago so pointing the small scope at the sun whilst using the dual mount meant also pointing the large, unfiltered telescope at the sun, this is potentially extremely dangerous not only for anyone who might accidentally look into the wrong eyepiece but it could also easily set fire to the observatory!
So I made a dust cover out of left over scraps of plywood, which made me happy:
Now I can safely observe our nearest star :)