This is how letter s glyph is built:
{sym: 's', model: ['(>3(,01,2(',')2,<)4<)']}

Where [model] is an array of two 'column','column' each 6 cells high. Digits mean consequent united cells and digit with zero means gap of a certain size. Symbols ‘<>’ are for left and right side dashes and parenthesis ‘()’ mean left and right corner roundings. Their position before a digit or after one determines whether top or bottom side will be affected. Different cell groups inside of 'column' are separated by com,mas.

Custom glyphs

    Create them yourself

Initial glyphs