Classroom Sentry is a remote Aerosol dispenser system. It uses a non-lethal pepper spray and teargas mix to deter an attacker. Classroom Sentry is our first attempt to give some control back to students and teachers in a challenging scenario. Its compact size allows you to mount it over a closed classroom door. You can build it yourself in eight simple steps. It takes about five minutes to build and has five components. Please watch the DIY video below for information to build a Classroom Sentry.