I used so much red gel that it made the fondant sticky.  On Valentine's Day cakes I sprayed them, but that doesn't work if it is part of a cake...like a popcorn box cake....

Hi, the best thing to do is to buy your red and black fondants. Check on internet to see who sells what colors. Satin Ice,  Fondx,   Fonderific,  etc. hth

I use powder colors for many of my colors, especially the red and black.  Using powders does not change the fondant like using a lot of the gel does and they do not fade like the gels.
 

You can paint the red part on with food coloring. Try cakedeco. com for pre-colored fondant. Not sure if you need a tax number for them....