Thanks for all the comments........ my gray matter, stimulated and working O.T.
This is what I came up with.
First photo,
1. pencil line for the curve. Then tape on top.
2. Cut the tap to shape,
3. Used the cut off part for paper pattern.
Second photo,
1. Used that paper pattern to shape a 1.5x1.5 Sq styrene
strip for final location of styrene sheet.
2. Drilled .8mm holes for styrene rod both sides of strip.
3. Rolled and shaped styrene sheet fitted between rods.
I will glue the rods to both sides of the strip. This should hold fast. Not
having to rely on a thin Edge that would probably fail. Now I'll pile on
the filler, of some kind to both sides of the strip and shape! Easy peasy!!!
Last, a bit of gluing up...................