First, cut a small piece of tape to protect the thumb.
Then cut a second piece to build the strap of the thumb protector.
Combine parts 1 and 2.
Make sure that the parts in contact with the baby are protected with tape and that no adhesive is exposed.
Put the thumb protector on the baby's hand as soon as they fall asleep.
The thumb has to be completely enveloped by the guard.
Staple the tape to adjust the size of the strap to fit the baby's hand. Be careful to leave no metal protrusion that could hurt the baby!