This snap-setting gizmo might make you cry. It's hard to use and you frequently end up with a snap that's only half-way on, and you have to pry it off the fabric, which oftens means you damage the item to which you are applying the snap. I hate that! It makes me so mad!!
Following the directions on this package could also lead to tears. They tell you to hammer the snaps, without offering a way to keep the plastic on the front of the snap from cracking under the hammer blows.
After applying many snaps, and suffering through many failures, I came up with my own way to set snaps like these.
Here's what you will need: the four pieces of the snap, two thread spools, a piece of scrap fabric, a hammer and a pencil. (Oh--and an item in need of a snap!)
Start with the front of the snap. Find the spot where you want it to be, and push it into the fabric. Since you are probably pushing it through several layers, the prongs will barely be showing on the back. Use the pencil eraser to push the fabric down onto the prongs, so the ends of the prongs are well-exposed. (See how chewed-up my eraser looks? It has helped me with a lot of snaps!)
To fasten the "outie" part of the snap, start by placing your scrap fabric on top of one of your thread spools; this will cushion the snap. The center of the spool has a round hole; center the snap over the hole (you will have to feel around for it, since the scrap of fabric is covering the hole). The hole will cradle the snap and provide even support around the edge, so when you hammer it, it won't crack.
Center the "outie" part of the snap on the exposed prongs.
Now center your second thread spool over the "outie". Hold the spool firmly with one hand, and whack the spool with the hammer four or five times. Remove the spool and check the snap; if it doesn't seem tightly attached, you didn't hammer hard enough. Replace the snap and spool, and hammer it harder! (I usually warn other people in the house before I start hammering!)
I don't have a picture for the other half of the snap, but it's the easy part, so I will just tell you: mark the spot on the fabric where you want the other half of the snap to go. Push the "prong" piece up through the fabric from the bottom at your mark, again using the pencil eraser to push the fabric down and expose the prongs. Center the last piece of the snap on the prongs (but check to make sure the deeply-grooved side is FACING DOWN; otherwise it won't hold). You only need one spool this time, because all the hammering in the world won't hurt this half of the snap! Just put the fabric item on the workspace, center a thread spool over the snap, and whack it hard with the hammer four or five times.
Hooray, you did it without breaking the snap OR crying!