Myself, I made rank and unit patches using MS Paint, then printed them out on white decal paper...Depending on the unit, some patches are so small that you can't get any real detail, while others, like that horse blanket that the 1st Cav wears, are easy...
For 120mm figures, you'll need name-tapes and rank (depnding on the uniform and body armor) as well as the SSI and flag. Just remember that the US Flag on the right sleeve goes on with the blue field facing forward..
These are my 1/35 scale decals..