If I mix pre-made red fondant with some red gumpaste that I've made, will the two colors mix into one shade of red, or will I have streaks? I don't have an airbrush.
I have mixed white gumpaste with coloured fondant and have not had a problem with streaking. You may need to microwave it to soften it a bit. It will mix better.
If you knead it together properly/long enough, it won't have streaks.