Think I quit the project, the V35 enlarger with a 63mm lens, extension tube, under lens filter - now yields 6 inches of "leg room" - tis enough for me to end this hunt for a unicorn red filter. Messing with a glass red filter, sandwiching or whatnot will not matter anymore considering I've the room I need -(pix shows ruler ontop of easel frame - 6 inches to work with ):