Courtesy of Woodsmith mag / TV show.
I hope this simple jig helps someone else out as well : )
Of course you can cut multiple slots at the same time by adding more cutters if you desire .
I think this would be quick and easy versus some of the other jigs used to hold the frames up in a vertical position. Enjoy : )
-- When you arrive at my front door, please knock softly but firmly. I like soft , firm, knockers : )