you'll need: your purse lining, set of magnetic snaps, two small pieces (scraps) of interfacing, a screwdriver, and scissors.
1. each set of magnets will include two discs to be placed on the wrong side of the fabric to secure the magnets. start by finding the center of your lining fabric and measuring down 3/4" plus your seam allowance. make a dot or small x in that spot. place the disc so that the center hole lines up with your mark. draw lines through each of the holes (close-up below).
2. you can do this separately on both sides and then cut small slits where you have drawn the lines. typically, i just line up the two pieces of lining fabric and cut through them together, but this can go wrong easily, so take care with that approach ;) i find it easiest to cut the slits with the point of my embroidery scissors. you just have to be careful not to push too hard, because you don't want to make the holes too large.
3. use the same process to make two slits in each of your scrap interfacing pieces.
4. place your first magnet through the slits so that the magnet piece is on the right side of the fabric. for whatever reason, i always use the male magnet on the zippered pocket side of the bag and the female on the pouch pocket side. you know, because at one point i randomly decided that's the way it's supposed to be. but i won't judge if you do it the other way around. promise.
5. turn over to wrong side of lining fabric. place one of the interfacing scraps over the prongs. (if you are using fusible interfacing, place the shiny side toward the lining fabric. you don't need to iron it, but this assures that it won't end up sticking strangely to your exterior fabric at some point.) then place one of the discs over the prongs.
6. use your screwdriver to bend the prongs outward. some people prefer to bend them inward, which in most cases is probably fine, but i've found this way to be sturdier.
7. repeat for inserting and securing magnet on the other side of lining.
and that's all there is to it! go you!!
previous madeleine mini-tutorial links: