A cap for accommodating a compound includes a body with an opening. The opening penetrates from an upper to a lower end portion of the body by a first length. A membrane seals a lower end portion of the opening. A lid is removably coupled and moveable relative to the body. The lid includes a protrusion extending downwardly from an interior surface of the lid by a second length greater than the first length. The opening accommodates a lower end portion of the protrusion. A spacer removably couples with the lid and interposes between the lid and the body. The spacer configurable between a first state in which the spacer is engaged with the lid, which prevents the protrusion from penetrating the membrane, and a second state in which the spacer is disengaged with the lid, which allows the protrusion of the lid to penetrate the membrane of the body.