An apparatus and method for forming tow-based absorbent structures having a single casing sheet are disclosed. The apparatus has a tow supply mechanism for providing tow material, a particulate matter supply mechanism for providing particulate matter, and a casing sheet supply mechanism for providing casing sheet material. The apparatus also has a vacuum draw roll having a foraminous center surface that has a width defined by a first edge and a second edge and is rotatable about a first axis. The vacuum draw roll is positioned to receive the tow material, the particulate matter and the casing sheet material to form a open core composite supply. The apparatus also has one or more angled surfaces positioned to create one or more obtuse angles in the open core composite supply, and one or more folders to further fold the one or more obtuse angles in the open core composite supply to form a folded core composite supply.