With a steady hand and a flat artist's brush, you should be able to paint the red blocks by hand.
Not part of the OP question, but thought I would mention it anyway - on some of my borders, I wanted a textured look, tyre tracks in the mud, rough ground etc. To get the effect, I used acrylic mastic, and worked it with a spatula to the effect I wanted. Then when it was dry (day or so) painted it with normal acrylic paint.
Tom.
Not part of the OP question, but thought I would mention it anyway - on some of my borders, I wanted a textured look, tyre tracks in the mud, rough ground etc. To get the effect, I used acrylic mastic, and worked it with a spatula to the effect I wanted. Then when it was dry (day or so) painted it with normal acrylic paint.
Tom.