DEFINITIONS:
Drogue bag: the bag in which the parachute lives.
Height: the dimension in the axis of the rocket.
REQUIREMENTS
There shall be space for a cylinder with a volume of at least 80 cubic inches with the ratio of its diameter to height being between 2:3 and 6:1. OR There shall be space for a rectangular with the same volume. Neither the width or length of this rectangle shall be less than 1.5 inches. This space is for the drogue bag.
There shall be at least 25 cubic inches of volume below the drogue bag for the motor section riser and hardware. This space may be cylindrical, or a rectangular prism. It must have a minimum height of 1 inch. Nothing shall obstruct this space.
There shall be at least 12 cubic inches of volume above the drogue bag for the drogue lines, hardware, and riser. This space may be cylindrical or a rectangular prism. It must have a minimum height of 1 inch. Nothing shall obstruct this space.
It is preferable for all three volume to be either boxy or cylindrical. If they are boxy, then it is preferable that they share a width or length dimension. If they are cylindrical, then it is preferable that they all share the same diameter. This simplifies the construction of the drogue bag and line containers.
No recovery components shall come into contact with a surface exceeding 300 degrees.
No volume shall sit, slide, or brush up against a sharp edge or corner that could snag or cut it. Nor shall the members of the of the volume be able to vibrate into such a position.