One of the steps in making your own sketchboard involves spending a few quality hours alone with your board and a hand-powered device known as a scraper. As the name implies you scrape things with a scraper. Unlike sandpaper it creates shavings not dust. Very thin shavings that fall on the floor or at the least are easy to clean, unlike the dust that comes from sanding epoxied fiberglass. I like scraping waaaaay more than sanding. Both are necessary, but I think scraping is better. Anyway, scraping smooths the surface, getting you one step closer to a finished board with a glass-like surface on which you can draw.
Because scrapers have a straight edge to them, the first thing that you notice are how the highs get scraped off and the lows remain untouched. This is quite handy in terms of finishing the surface. Dried epoxy turns cloudy when it is scraped as you may be able to notice in this second image, but the lustre and color of the underlying wood is restored when the final coats of varnish are added on to the surface.