I use liquid cement or Mr. Surfacer 500 or 1000. I use an old tooth brush to stipple the surface when I use the liquid cement and a sponge for the Mr Surfacer. Just depends on how rough the cast effect needs to be as to how much I rough it up with the brush or sponge. I have also used a dremel tool to get a cast effect as well by using a round ball cutter bit to bounce around on the surface I wnat to look cast. It takes longer using this method but looks good. I ahve attached photos of all three methods. 1st set is the liquid glue method, 2nd set is the Mr. Surfacer method and the last set is the Dremel tool method.