In my last order from Litko, I bought 25 2" by 1" "pill" shaped bases. I have been reading the new Pickett's Charge rules, which call for several aides de camp per side. I think this would be a workable way to denote couriers.
Three of the figures are from Sash and Saber, while the bald Union officer removing his cap is from Old Glory. I hope to put on a Pickett's Charge game this year.