Hi Spidey,

If you don't have a much of a changing radius, the tried and trued way is tried and true, but using mine:

When filing between the forms, my file is perpendicular to the strips (but at the desired angle up or down) but it hits the front side of the rear form and the back side of the front. If I kept the file perpendicular, after filing between two adjacent pairs of forms, there would be a nub left that is the thickness of the strip in the inward direction and with a width that matches the width of the forms. Say 1/4in (strip depth) by 1/2in long(form ply thickness). I could just slice this off, but instead make the nub smaller by angling the file inward(at exactly the same up or down angle) to make the nub smaller.

If I angled at 45 deg, the nib left would be about 1/8"(half the strip thickness) by about 1/4" long(half the form ply thickness). Easy to slice off as I lay the exacto knife at exactly the same angle of the filed strip - I can follow the angle and the surface at the front quite easily.

-mick