You can use this technique to make painted cut-outs or you can apply the paint directly on the cake.
3.
Use a brush to apply some paste colour on the rolled out paste. The colours you use will get mixed together so choose colours which look good once combined together.
Don't apply too much colour on. You can add more later if there's need. The more you apply, the longer you will have to wait for it to dry.
The paste colours give a slightly shiny finish. If you want a matt effect, use dust colours dissolved in alcohol (see step 12).
I used Wilton paste colours (Sky Blue and Lemon Yellow).