A composite material blank comprising an elongate blank body extending between a first end face and a second end face; said blank body extending in a longitudinal direction, parallel to a longitudinal axis thereof, and having four peripheral sides; each said first and second end face having edges which define a trapezoid shape; wherein the peripheral sides of said blank body connect the edges of said first end face with the edges of said second end face; and wherein said first trapezoid end face is inverted in relation to said second trapezoid end face. A method of manufacturing a composite blank, and a wind turbine blade root insert which may be formed from a blank.