A scanning 3-D printing system comprises a printing platform movable in a printing direction and in an indexing direction, the printing platform comprising a printing head configured for dispensing building material while the printing platform is moving in a printing direction one pass at a time, and layer by layer, a roller configured for leveling the dispensed building material one pass at a time, wherein the roller is rotatably mounted on a roller axle, and wherein the roller axle extends over all passes of the printing system and is stationary in the indexing direction, a scraper configured for scraping excess building material off the roller, and a trough configured for collecting the building material scraped off the roller.