Inserts can be formed with elution characteristics to cause the inserts to elute an antimicrobial agent when subject to a fluid within a medical device. An insert can be formed with a desired geometry to allow the insert to be compression fit within a medical device to prevent the insert from moving or becoming dislodged once inserted into the medical device. The material may also be hygroscopic so that the insert swells when subject to a fluid thereby enhancing the compression fit of the device within the medical device. In some cases, the material can be reinforced using an internal structure. Inserts can be formed in many ways including by casting, thermoforming, or extrusion. In some cases, the inserts can be formed using a peel-away sleeve or material. The peel-away sleeves can be formed of a non-sticky material which facilitates removal of the inserts once the inserts have cured.