I wanted to make a proportional string spacing rule and found out that adding small spaces requires some experience which I do not have. So I developed my own lazy way to make a perfect scale:
A proportional string spacing rule in five minutes with OpenOffice Calc:
1. Set horizontal border cell lines to be visible.
2. Set each string height adding you preferable increase (I added 0,1 mm to each line aka 6 - 6,1 - 6,2 ...)
3. Print it out on a thick paper or a cardboard.
4. Cut the paper margin.
I believe it will work well with any spreadsheet processor like MS Excell etc.