You do not have to be 21 years old to buy an alcohol flask. The legal drinking age in most parts of the U.S. is indeed 21, but this law only applies to the purchase and consumption of alcohol itself, not alcohol accessories and paraphernalia such as flasks.
The age restriction on alcohol is mainly in place to regulate the consumption of alcoholic beverages, as they can have potential health and safety risks, especially for young individuals whose bodies may not be fully developed. However, the purchase and possession of alcohol-related items like flasks are not considered to pose the same level of risk.
Therefore, it is perfectly legal for someone under the age of 21 to purchase an alcohol flask and give it as a gift to an older relative or friend. The flask itself is not considered a controlled substance or a direct facilitator of underage drinking. It is simply a container used to hold and transport alcoholic beverages.
It is worth noting, however, that even though it is legal for someone under 21 to purchase a flask, they should still exercise caution and responsibility. It is important to respect the laws and regulations surrounding alcohol consumption and to discourage underage drinking.
In my personal experience, I have seen instances where individuals under 21 have purchased flasks as gifts for older family members or friends who enjoy alcohol responsibly. It is seen as a thoughtful and practical gift, especially for those who enjoy outdoor activities or attending events where alcohol may not be readily available.
To summarize, the purchase and possession of an alcohol flask is not restricted by age, as it is considered an accessory rather than the alcohol itself. However, it is always important to approach alcohol consumption responsibly, regardless of age.