I have a canvas where I will install the frame. I don’t want the lip to cover the full rabbet width of the top of the painting in particular. I.e., if the lip/rabbet width of the frame is 5/16″, I want it just to cover 2/16″ at the top, which will still be enough for the frame to overlap.
What would be the best thing to use as this 3/16″ spacer between my canvas and the frame?