I use the rabbited joint, I cut several boxes out and the run the ends through the router to get the frame rest and do that end on the sides for the rabbit. I use Gorilla glue, tightbond or liquid nails which ever I have at that time. Put staples in and they are ready to paint, put two or three coats on and store for a few months. Good luck OldMech.
When you go to paint, go by local stores and ask about wrong mixed colors (exterior paint), you can get it at a good price.
Oooh... Excellent Idea! Going to town tomorrow, will get my name in with the places I know that mix paint. Thanks!