Hello, first of all, I wish you all the best.
I don't know what kind of souvenir you are going to give. If it is just some simple small gifts, such as some candies or snacks, dolls, etc., just put them on the wedding table and let the guests take them away when they leave. If it is some very special souvenirs, it is recommended that the newlyweds personally present them after the guests sign in and receive the blessings.
Some DIY things are more popular now. Since it is a wedding souvenir, of course, something that can reflect a sweet feeling is the best, so I recommend giving a DIY blessing chocolate. This kind of chocolate can be ordered online. Just send your blessings to the online store. It is very unique, and chocolate itself is also a symbol of sweetness, which will make the guests feel that you have prepared the gifts very carefully.