Manufacturing process to reform glass tubes

A method for modifying the shape of a hollow structure, comprising:

• providing a hollow structure comprising a glass material having a cross-section with first and second diameters defining a first aspect ratio;
• heating at least a part of the hollow structure to at least its glass transition temperature, forming a malleable hollow structure;
• maintaining a positive pressure inside the malleable hollow structure to form a pressurized hollow structure;
• and
• pressing against a first side and an opposed second side of a heated part of the pressurized hollow structure, using opposed platens thereby forming a hollow tabular structure having first and second opposed generally flat faces and a second aspect ratio greater than the first aspect ratio;
• wherein spaces between the opposed platens adjacent opposite sides of the heated part are open.