How to bend at a right angle a classic float glass sheet (the glass of your window)? Attention, I'm talking here to get a true right angle acute, tight, not a soft round wave obtained easily by simple thermoforming of the glass sheet. Scientists of Fraunhofer have developed a method of folding a single sheet of glass at a 90 degree angle without changing the structural qualities and optical properties of the glass. The trick is to place a glass plate in an oven at 500 degree, so just below the point of transition temperature where the glass becomes malleable. A laser is used to heat the glass a little more, but only along a straight line that goes down the middle of the sheet - the rest of the glass remains at 500 degree and therefore rigid. When the supports are then removed from one side of the glass, gravity bends the sheet along the softened line, naturally forming a 90 degree angle. Once the folded glass cools, it becomes fully rigid again.
For more details, it's here (but in German).