To get the “fill” font I just deleted the outer contours.
Well, I have not seen the font with which you are working, but when I produced my Galileo Lettering Enamelled font from a copy of my Galileo Lettering font, I deleted the inner contours, not the outer contours.
The fonts are available at the following web page, just over half-way down.
There is a thread about the Galileo Lettering font family in the Gallery forum.
The third post in the thread is about the producing of the Galileo Lettering Enamelled font.
In that thread I wrote as follows.
quote
I produced the Galileo Lettering Enamelled font this morning by adapting a copy of the Galileo Lettering font.
I simply removed some of the contours, namely some of the counterclockwise contours.
end quote
The counterclockwise contours are the inner contours.
I hope that this helps.
William