TabularText
TabularText helps you create files composed of lines with fields in fixed positions. Yes, people still use that. Yes, a more structured format would be best.
Example, writing
builder.line do |l|
l.field 'Name has 30 chars', 30
l.field 1, 6
l.field 27
end
will generate
Name has 30 chars 00000127
A more detailed README will be written the day anyone thinks about using this.