On that one I first sprayed the MDF with multiple coats of gloss blue spraypaint. After it was dry I covered the board with some of the 3M masking product that Inventables sells and used a V Bit to carve through it exposing fresh wood in the cuts. The white paint was just acrylic paint, it took mulitple coats since it soaks into that freshly cut MDF.
Overall it worked OK…there was still some touchup I had to do after removing the masking. I haven’t done that method many times after…it works in a pinch if you are going for a clean look. More often now, I use multiple layers of paint and sand back giving more of a rustic look (also it is MUCH easier). Cut the MDF, put a few layers of chalk paint on, paint the lettering and sand the whole thing back to get the look I want then spray it with a few coats of waterbased poly. Here is an example.
Blair