Here is an example of the elastic strings you can get.  The one on the left you can buy at any fabric store or department store.  The price ranges from $0.75 to a couple of dollars.  

  The elastic at the right I buy at a fabric outlet store.  It comes in a roll and costs about $25.00.  I get this quantity so I can set up a target at each clinic, have the girls compete to see which one will hit the target first, to win the target.

  The gold elastic string is just raz ma taz.

  This is a great training aid.  The girl pitching gets instant feedback of her progress.  She can keep score and each session challanges the last session.  Or she can compete with another pitcher.  You will see 10 yr olds competing against the best pitcher in town.

You can put those little bells on the corners, and watch their eyes light up when they hear the noise.

   My girls like to play pig against each other, and especially against me.  Sometimes the catcher will move the glove and it is hard to know wheather they hit the target or not.  With the string there is no doubt.