Many ways to attack a problem.
The problem is actually quite trivial, if we employ some
mathematics. By the way if math is a dirty word for you, do not
bother to read any further. Only brave, mathematically inspired souls
should venture beyond this paragraph.
Let’s unfold the bezel. What we have is a rectangle. To match the
bezel to the curved surface means to find a geometrical shape where 3
sides are matching the rectangle of the same dimensions, and the
fourth side is defined by a graph of the function of the surface we
are trying to match with.
By saying that we trying to find geometrical shape, we are saying
that we want to know the area of such shape. By phrasing the problem
in this way, we reduced the problem to finding an integral of the
function defining the intersection of our bezel with the curved
surface we are matching to.
Plainly speaking, an integral is simply a sum of areas of
rectangles, arranged in such way, that by varying the height of the
rectangles, the tops are approximating the graph of the surface
defining function. Theoretically, the width of the rectangles is
tends to zero, but for our purposes, it does not have to. We should
choose the width which only provides sufficient accuracy. There is no
reason to bother with smaller values.
Once we understood the mathematics behind the problem, the practical
implementation is quite easy.
Make a bezel equal to required height + maximum height of the
surface, we are matching to. A little bit if extra height would not
hurt. With dividers opened to maximum of the surface height, mark
the line all around the bezel. Take fine snips and divide the marked
off part of the bezel into strips of 1.5 - 2 mm width, same way you
prepare your solder. Do not go beyond the marked line.
Now, the marked part of the bezel is a sum of rectangles that we
talked about. To find an integral all we need to do is simply the
following. Gently tap the divided end of the bezel against the
surface. The portions of the strips that are extraneous, should bend
away. After a few taps, you should have the contour matching the
surface. Open dividers a couple of millimeters and using this contour
scribe another line on the bezel above the contour. Cut off divided
portion of the bezel along this line and we done.