Traditionally, the gifts given to a bar mitzvah boy would be tefillin—though ideally these should be worn at least a few months ahead to practice—and a tallit in certain communities. In Ashkenazi Orthodox families, the tallit is usually reserved as a wedding present for the groom, but even so some people might get one as it is traditional to wear one when reciting from the Torah, on the bar mitzvah birthday or otherwise.
Girls might traditionally be given shabbat candlesticks or Jewish jewelry for a bat mitzvah gift. Many young women in Reform and Conservative communities also receive and wear a tallit in a feminine design.
Some timeless gifts for child of any gender celebrating this milestone might be a tzedakah box, Jewish wall art, or a siddur (prayer book). And whether it’s a new suit or a special bat mitzvah dress, it may also be nice to get something for this very young adult to feel good in on a momentous day.
It is always a good idea to give over resources to help the very young adult to succeed in the future, so if you want something that will set anyone up well without being as materialistic, it is quite popular to give Jewish educational gifts, including books of Torah.
These days, many people like to give personalized items, whether jewelry, engraved Judaica, or special cards. Whether a personalized tallit bag, kiddush cup, kippah, or name jewelry, these gifts add meaning and memorability to an already significant occasion. This can also add to the sense of familiarity to a bar mitzvah gift if not attending.
Money is often a preferred gift option as well, though whether this is as a gift-card, stocks and bonds, or good old-fashioned cash is up to you. Money, especially that can be saved up for important uses later, is a nice gift you know will go towards something timeless. Traditionally, this is given in multiples of 18, as that is the numeric value of חי meaning ‘life’.