A thumb guard for your wood carving tool hand is a necessity for your safety as a wood carver. Thumb guards will help to protect your thumb while wood carving, especially when you are using a paring cut that causes the carving blade to be directed towards the thumb.
There are several options to choose from, depending on how much you want to spend. Leather thumb guards are sold commercially. You can also use a gauze type tape that only sticks to itself to wrap around your thumb. Another option is use masking tape or duct tape wrapped in layers. Yet the most economical, is to use a pair of work gloves and cut the out the fingers so that only the thumb is covered and held on by the palm of the glove. You can then wrap tape around the thumb to add value to the protective nature of the thumb guard.