Cut pieces of thick foam into squares large enough to wrap once or twice around each bed rail. Foam that is used as mattress padding is ideal; either purchase new padding or reuse existing padding you already own. Wrap a piece of the foam around the bed rail before cutting for fitting purposes. Each foam piece should cover the entire length of each rail. Use a knife or large fabric sheers to cut the foam into appropriate-sized squares.
Wrap the foam pieces around each bed rail. Secure the foam with heavy-duty tape such as duct tape; clear tape or glue can become undone quickly. Maneuver each foam piece so the tape is facing outward instead of the inside of the crib.
Check each individual rail to ensure the foam is secure and add more tape as needed. Use extra padding if desired by placing long thin pillows against the inside of the rail. Cut and wrap pieces of old towel as additional padding. Use duct tape to secure the towel pieces.