For the bows on these streamers, we used two very different ribbons in the same color. The streamers themselves, and the centers of the bows, are of velvet ribbon that is 7 millimeters wide; the bows themselves are of satin ribbon that's 24 millimeters wide.
Use scalloping shears to cut the satin ribbon into 2-inch segments for the bows, and use regular shears to cut the narrower velvet ribbon into 3/4-inch segments. You will need 40 of each.
Wrap a narrow ribbon around the center of each satin bow, and glue at the back with high-tack adhesive.
Attach the bows to the streamers: Glue them to a 1-yard-long piece of the narrow velvet ribbon, spacing them about 1/4-inch apart and starting from each end.
Be sure to leave 8 inches at the center untouched for wrapping around the handle of your bouquet.