Text on negative

Trying to make a feature with a frame that will be used both for the online space, and for headings in text pagination.
The feature includes 2 variations 1. Linear frame 2. Negative frame
My problem with the negative is that it simply hides the content
I would appreciate an idea if you could do it right to get the negative text
I will mention that I tried chanze direction
Screenshot_249.png
Screenshot_248.png

You might need ligatures, as two overlapping glyphs will be drawn on top of each other.

What do you mean?

I tried to make composites, does not help!

Two or more overlapping glyphs just won’t work, so you need to make a new glyph and use a ligature substitution.

It works fine for me. I made a composite glyph with five glyph members :S, E, N, D, and the custom signpost glyph. If you need different signs, you may need to create multiple signpost glyphs of different widths.
Composite Glyph.png

As you can see, the width of each sign needs to be different to get the right spacing.
ToDo.png

9.gif
I think I was misunderstood.
It’s a live text feature that I’m embedding in Poni
It is built from two frame halves
between which there is a longitudinal inference,
depending on the need and the amount of characters.

It is not a ligature or a single glyph

And this is also one of the places where I want to apply detection of the number of characters
and applying a variable value to them (frame length is appropriate in this case)
Then it can be used within text without the need for manual adjustment - by the slider
but by activating the appropriate feature
10.gif

Do as he did:
https://beitalef.com/היצירות/בראשית
(Actually what he did, is that he added a line above and below each letter, and thus each letter that is added, adds its own line…)