I wanted to use my mini-lathe for turning a hemispherical surface. After some deliberation I decided to create a fixture for the chisel, which leads it by circular path. The device is welded from two main parts: flat part secures the circular path while the square tube holds the chisel in the height of workpiece axis.
The fixture sits on the chipboard which is fastened to the lathe bed.
You can see how it works on the short video. (Video is so short, because it is created from 10 still photographs. I forgot that my camera can also record a movie.)
Another video with the function of my sphere jig: