Does a Tallit need to be made by a Jew?

Hi folks! I am not Jewish, but my sister is. Her eldest son will be turning 13 in December and celebrating (I don’t know if that’s the proper term) his Bar Mitzvah soon. I am a weaver and would love to make his Tallit. I know that the Tzitzit have special knots and also know that they can be purchased separately and added to the Tallit after it is woven. So here are my questions: does a Tallit have to be made by a Jew? Are there special prayers said over it to “make it Jewish”? Can the tzitzit be attached by a non-Jew? Would this be a weird or inappropriate thing for me to do? Thanks so much in advance for any advice!