Draw in the bars?
There was a font which did this: https://www.quora.com/What-font-should-I-use-to-type-Roman-numerals but it seems to not be available now (you’d need an OpenType aware application to do the typesetting in)
The list of fonts which purportedly support this feature is fairly extensive: http://www.fileformat.info/info/unicode/char/2162/fontsupport.htm