butter cream- almost stucco look?

Great question! I, too, would like to know how to do that.

On the food challenge last night they used a small whisk broom which created a very rough texture.

I have used a large soft paint brush or even crumpled waxed paper.

I have used a cheap sponge, that I bought in a bag with a lot of other sponges, I washed it, microwaved it, washed it again and microwaved it again, washed it, let it dry and then just patted my BC frosting with it, made a stucco looking surface. The washing and microwaving was to make sure that there was nothing in the sponge that would cause any problems.