The invention relates to a method of customizing a nail-biting and/or finger sucking treatment solution, and a kit for providing a nail-biting and finger sucking treatment that is customizable for a wide range of afflicted users seeking to break a persistent nail-biting and/or finger sucking habit. In exemplary embodiments, the composition kit includes two separate containers, a first container having a nail growth-promoting, waterproofing composition that may be applied directly on a user's nails； and a second container may include an additive for customizing a bitterness factor of the first composition. Typically, the first container includes an applicator such as a brush. To facilitate adding the additive in a manner that is easily customizable, the second container may include a dropper for adding small doses of the additive composition to the first composition. The customizable kit allows the user to safely adjust the bitterness so that the treatment remains effective.
