Don,
I use a piece of 2X4 to hold each part to be painted. A separate piece for each part. I drill holes in the 2X4 spaced to match the hinge holes in the part. (I use Robart hinges). I use pieces of coat hanger wire about 8 inches long inserted into the holes in the 2X4 and into the hinge holes in the part. You can move each assembly to and from the paint table to keep overspray from getting on other parts. If you use slot type hinges, you can use thin pieces of plywood or sheet metal taped to the edges of the 2X4 and inserted into the hinges slots. Hope this makes sense. Easier to do than to explain.
Paul