How do you fit snap fasteners, (not sew on ones)?
With a hammer, You have an inner and outer piece for each half of the snap fastener. You put one piece on the inside, and one piece on the outside (one piece must poke through the cloth), and then you use the “metal things for helping to fit them”, and hammer one of the metal things which crimps the inner and outer parts together, while supporting the part you’re not hammering. I hope this helps, it’s a bit hard to describe in words, especially without seeing the metal helper things.
