Bubblegram

A laser glass sculpture of a caffeine molecule

A bubblegram (also known as laser crystal, Subsurface Laser Engraving, 3D crystal engraving or vitrography) is a solid block of glass or transparent plastic that has been exposed to laser beams to generate three-dimensional designs inside. The image is composed of many small points of fracture or other visible deformations and appears to float inside the block.