Demo Cup

Originally Demolition Cup, a registered brand name for an explosive which could easily be fixed to walls, but now used as a generic term for a variety of stick-and-run explosive devices. While many of these are suitable for demolition projects, some are merely for show.

The cup is generally a hemisphere made of flexible or gelatinous material, with its edges coated with thick layers of some temporary adhesive. In original demolition cups, this is an epoxy resin which quickly forms a strong bond to whatever wall it is slapped on to. When attached to a wall, a chemical reaction begins, filling the interior of the cup with some gas. This may be flammable, smoke or some other gas, which builds up pressure inside the cup. Eventually, this may trip a pressure sensor or chemical trigger, causing the device to explode.

Some cups (such as the original) punch a hole through the wall, releasing shrapnel on the other side. Others (commonly used to cover retreating troops) will burst under pressure, releasing smoke and grit as well as burning any pursuers.