Glass block has become a fairly widespread construction material. As with concrete block, glass block are currently limited to square and rectangular blocks.

This limits the architectural applications of glass block to straight vertical walls and square corners.

Glass block is manufactured by first forming two pieces of glass, and then joining them while the glass is still warm enough to be moveable (at around 800 degrees F).

The two pieces are pinched together in a two-piece mold and allowed to anneal or cool slowly to reduce thermal stresses and obtain a thermally stable object.