A flower girl basket can be constructed with a pre-bought basket, ribbon, cardboard and flower petals. If the flower girl is going to be tossing petals during the ceremony, the basket can be filled with flowers. Otherwise, the basket's opening can be covered with cardboard and it can be fully decorated.
Take the basket and decorate its edges and handle with colored ribbon. These ribbons can be in the same colors as the theme of the wedding or matching the flower girl's outfit. Afterward, if no petals are going to be thrown from the basket, cut out a piece of cardboard in the same area as the opening of the basket and cover it. Finally, cover the basket with flowers or flower petals using glue.