-er: A person who paints (painter)
-ing: The act of painting (painting)
-ed: Past tense of paint (painted)
-able: Capable of being painted (paintable)
-ful: Full of paint (paintful)
-less: Without paint (paintless)
-work: The result of painting (paintwork)
-shop: A place where paint is sold (paintshop)
You can also add prefixes like:
over-: To paint excessively (overpaint)
re-: To paint again (repaint)
These are just a few examples, and the specific suffix that you use will depend on the meaning you want to convey.