Hi Wolfgang. Have you given any thought to a few pieces (or a full set) of the 11th Indiana Regiment (Wallace's Zouaves)? They were a Union unit formed in 1861. They wore overall gray uniforms with minimal red trim around the neck, front, and waist of the jacket. There were no buttons on the jacket which hung open to reveal a standard Union Blue shirt. Kepis were gray with vertical piping on the seams and a red top. Officers may have worn an all red kepi. At least one artist had depicted an officer wearing a gray vest with a red center placket and and gold buttons, and standard shoulder rank tabs, but with a red background. Everything else was standard Union gaiters and boots. All other equipment - belts, ammunition pouches, canteens, and weapons were all standard Union for the period. They kept the uniforms for the first few months of the war, but later switched to Union Blue with light blue trim.
I don't think anyone has done a figure (round or flat) of this unit.
Just a thought...
Cheers,
Glen