The snap end snaps to the pacifier, and the clip end clips to the baby's clothes.
First, I found ribbon I liked (the double sided ribbon looks the best in the end). I didn't want them too long otherwise it becomes a choking hazard, so I cut the ribbon to the length I felt was functional, but safe at the same time (the length ends up shorter than you cut since both ends fold in).
On one end, I attached a suspender clip (I actually bought some suspenders at the thrift store that looked brand new and cut off the clips to use) It was only about 75 cents for 4 of them compared to the $2+ for a set of 2 at Jo-Anns.
I looped one end through the slot and then folded the ribbon under and stitched near the clip to secure it.
The other end was a bit trickier. I used my Mom's "Snap Setter" to attach these - combined with the muscles of my husband to hammer them together. I tried, but aparantly, I am not strong enough. Her snap kit came with instructions on which pieces to pair together. But I also folded the end of the ribbon in before attaching the snaps so it was a cleaner edge.
The spacing between the 2 sets will depend on the pacifier you use. I use the Avent ones that have a really thin ring/handle thing. Other brands have a thicker handle, so you would want the spacing to fit the brand you use.