Developing chemistry & trays, contact frame (or a flat board and piece of glass), a bare lightbulb and a timer.
Ditto. You can even get away without the timer with a dim enough bulb. My first setup used a 7w nightlight bulb held as high as I could reach with the negative and paper between two glass panes laying on the floor. Exposure times were in the :20-:40 range which were easy for me to reliably just count off in my head. Being a few seconds off doesn't matter as much on a :30 exposure than it would on a :05-:10 exposure.