1. Prepare the stencil
Cut out the stencil and transfer the outlines onto the thermoplast with a sharpie.
2. Heat the thermoplast and cut it into shape
Fill about 1-2 inches of water into a pot. Heat the water to right before it boils. Put the thermoplast into the water and wait until it becomes soft. Make sure it doesn‘t stick to the bottom of the pot. This should take less than a minute. Take the thermoplast out and let it cool off a little bit. Then cut along the lines with scissors.
3. Mold your Catcher‘s Thumb Protector
Make sure it is still soft. If it has hardened, put it back into hot water. After it has cooled off enough to put it on your skin, shape it around your thumb.
To do that, place your left thumb on the wide side, with the thermoplast underneath. Then wrap it around your thumb, tucking the narrow piece unerneath the thumb. Make sure your thumb is in the same posititon as it will be in your glove.
4. Trim it to your fit
After it has hardened (cold water will speed up the process), try it in your glove. Now you can reheat and shape or cut your Thumb Protector to make it fit you.