Are you using Corwell's Pink Insulation foam or the styrofoam that has a bunch of little balls in it? The pink stuff is what ya need to use because you can't get rid of the texture of the other stuff. Basically I layer the pink foam with wood glue until it dries, carve things down either with a band sander or dremmel, do a final sand with a orbiting hand sander, and periodically sand by hand. After that I'll gesso each side several times, sand again, then put on several more coats of oil based polyurothane, then paint. This sword was painted with spraypaint, so the paint job is going to look that much more smooth (but you have to make sure the foam is totally covered otherwise the paint will melt it)