Abstract: A modular canister is provided for containing a missile for launch. The canister includes a set of four longitudinal assemblies, an electronics module, and a hatch module. The assemblies are attachable to form a rectangular cross-section chamber between fore and aft ends. Each assembly includes a wall extrusion and a corner extrusion. The electronics module connects to the chamber at the breech. The hatch module connects to the chamber at the muzzle. The hatch module includes an aperture cover, a door and a hinge. The door pivots on the hinge between a default closed position and a command open position. The chamber can receive or else launch the missile through the muzzle when the door is in the open position.