National Federation Cast Rule A Legal Cast Consist of the Following Steps: Cast or Splint must be constructed of an approved material. (No Metal or Plaster) Cast or Splint must be covered completely by a closed cell quick recovery foam material. Must be a minimum of ½”s thick. Athlete must have a written form signed by an licensed medical physician indicating that the athlete may participate in his/her sport while wearing the cast or splint. This form must be available to the official at the start of the contest. Paperwork and cast/splint must be available and shown to the game official prior to the contest.