The present invention relates to a tray made of corrugated cardboard sheet material, and to blanks for preparing such a tray having a polygonal cross-section. Said blank comprises sidewalls, raised edges or portions of raised edges on two opposite sides of an upper portion, and a lower wall forming the bottom (36) of the case. Each raised edge or portion of raised edge includes at least one rounded portion (34), and the bottom includes perforated surface portions (35) which have a shape complementary to that of the rounded portions, which are arranged opposite the latter, and are arranged so as to fit into the rounded portions of the tray from below.