It should be possible to use pictures of symbols or letters (for example saved in TIFF format) for making new fonts, which can be saved as TrueType fonts (.ttf). The best program for this would be one of the font editors, such as BitFonter.
Convert Aldus Tagged Image File Format (TIFF) bitmap image to TrueType font file.
We have found one software suitable in our database for this conversion.
Microsoft Windows software - convert tiff to ttf on Windows
A bitmap font editor
Convert from tiff file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.