there are two kinds of alternate letterforms:
(1) Those you can consider to use for text body and headlines.
(2) Those you can claim as experimental which are mainly used for logos and crazy posters.
Every letter of the alphabet contains a different number of acceptable (readability-wise) alternate letterforms.
I would like to know if there is any overview for typedesigners to see the range of possibilities in sans-serif typedesign?
I planned to design an overview about all kind of acceptable skeleton-shapes for body-text, but this collecting task
turned out to be not that easy.
Do you know any resources that could provide me help?
Thank you very much!
It depends on the typeface. All the glyphs you show here look like they come from different typefaces (except those on the first column).
Other than that, a knowledgaeble and experienced type designer would be your best resource, but it would be a job of work.
CIA Compendium by Jens Gehlhaar is an anthology of letterform skeletons found in sources “ranging from 15th century italics to geometric display faces, from Art Nouveau oddities to Apple system fonts”.
“I once even proposed that the toughest challenge facing AI workers is to answer the question: ‘What are the letters 'A' and 'I'?’”