The material used to create the thumb guard is thermoplastic splinting material.  It is manufactured in flat sheets in a variety of sizes, widths and consistencies.  My preference is the Synergy material, which is made by Rolyan and available from medical supply companies, such as Sammons Preston (which sells to the public).  The Polyform Light material also works well, but is slightly thinner than Synergy and doesn't finish quite as well as Synergy.

Splinting material has different consistencies allowing for more or less flexibility.  When creating a thumb guard, favor rigid material.  If you want to experiment with different materials, buy the student pack.  It offers a sample sheet of different types of material.  You can get two thumb guards out of each sheet in the student pack from Sammons Preston.

 

Cut a template similar to the one shown in the picture.  I'm a lefty, so the pictures throughout will show this being formed on my right hand.  The template in the picture represents how a right handed thrower should look.  The width of the template in the picture is a little over 4 inches and about 7 inches tall, which fits my hand.  Your hand size will dictate the size of the template.  A pair of heavy duty scissors will cut the material with ease.  When cutting the material, leave plenty of extra room on all sides, particularly above the top of your thumb.

 

Use a frying pan and fill it halfway with water.  Bring the water to a simmer and then cut back the heat on the stove to level 4.

 

Place a fork under the material and place it in the hot water for approximately 5-10 seconds or until the material loses its rigidity.  You'll know when it starts to mold around the fork.  Don't overheat the material and don't let it touch the bottom of the frying pan as it will stick to the pan.

 

Remove the material from the hot water and let it cool for approximately 5 seconds.  The material will be hot, so use caution.  Lay the material on the top of your thumb and focus your first form around the pad of your hand.  Hold to the shape of your hand until the material hardens, which will be 20 to 30 seconds.  Don't do any forming around your thumb at this point.

 

 

Reheat only the thumb portion of the guard and begin shaping the material around your thumb.  This is the longest and most important step.  Go slow and be patient.  You will have to repeat the reheating and molding process several times to get this perfect.  Don't let the two sides of the material touch together yet as they will fuse when hot.  Also be sure to wiggle your thumb slightly throughout this step when it's in the guard.  You do not want the guard to be skin tight.  Your thumb will expand while you're catching and it will be uncomfortable if you made your guard too tight.

Once heated and touched together, the material will fuse to itself.  Once you make the overlap of the material around your thumb and it has hardened, take your thumb out of the guard, reheat the thumb portion and work the seam together with your thumb and index finger.  Keep your index finger inside the thumb guard to support it while working the material flat with your thumb.  Make the seam as flat as possible on both the inside and out.  Keep reheating the guard to aid this process.  Once this step is complete, completely reheat the thumb portion, place your thumb back in the guard and wiggle one more time to ensure the form didn't change and you still have adequate expansion room.

Be certain to leave a gap between the tip of your thumb and the top of guard.  Otherwise, the guard won't offer as much protection in the event you catch a ball off the tip of your thumb. 

 

A good trick here is to insert a marble on the inside of the guard when finishing the tip.  Insert the marble and put your thumb in the guard behind the marble.  Reheat the tip of the guard and work the tip of the guard with your other hand.  Don't pinch the opening closed, but instead, "roll" it closed by going around the tip and rolling the material inward.  The marble will give you a hard surface to roll against, while maintaining the gap between the tip of your thumb and the top of the guard.  Leave a small hole at the tip of the guard to allow for airflow.  Once the tip is formed to your satisfaction, remove the marble by poking it from outside the guard through the small opening with a toothpick.

At this point, the majority of the molding is complete, but you need to eliminate all sharp edges as well as any interference with your wrist.  Once the guard has hardened, place it on your thumb and in your mitt.  Use a Sharpie marker to determine your trim areas.  Trim the guard so it does not reach the break in your wrist when you bend your wrist backwards (see picture of catchers mitt).  If you haven't done so already, be certain to flare the edge of the guard between your thumb and index finger.  You'll have to reheat the guard to accomplish the flare.  The flare will assist in protecting you against a jam and without the flare, you'll have an edge cutting into your hand.  There shouldn't be any sharp edges on the guard once you are complete.

This is a picture of your completed thumb guard.  The beauty of this material is its ability to be continually remolded.  If you decide there's something you don't quite like, simply reheat and remold.  You may need to adjust the thumb loop in your glove to accomodate the additional thickness of the thumb guard.  Good luck!

 

One note of caution: A guard may lose its form in a hot car in the summer.