Disinfecting cap for open female luer devices

A method of making a cap for removable attachment to an open female luer device, the method comprising:

• providing a mold comprising at least a first side and a second side, the first side comprising a mold core for forming a thread;
• injecting a liquid polymer into the mold;
• allowing the polymer to cool so as to form the cap;
• and
• after forming the cap, separating the first and second sides of the mold without rotating the first side;
• wherein the cap comprises:
• a body comprising an opening, a bottom, and a chamber defined between the opening and the bottom;
• a wall of the chamber comprising the thread originating proximate the opening and extending into the chamber, at least a portion of the thread having a height that increases as a function of increasing distance from the opening;
• a male post in the chamber projecting from the bottom towards the opening of the body, wherein the male post is spaced from the wall;
• a movable piston comprising:
• a central opening surrounding the male post;
• a top region extending from the central opening and comprising a sealing surface;
• and
• a flexible circumferential skirt extending laterally from the movable piston at an acute angle relative to the male post, wherein the skirt is a flange with a gap between the flange and the top region, wherein the flange is in slidable contact with the wall of the chamber;
• the method further comprising introducing a liquid disinfectant into the chamber between the bottom of the body and the movable piston.