I have become so fascinated with these little tools! The Ruffler, Tucker, Hemmers, Shirring foot, Hemstitcher, Blind stitcher, Zigzagger, Buttonholer, are the most common ones found now for sale on auction sites, in thrift stores and yard sales. There were also underbraider plates for sewing on decorative braid and cording, and embroidery attachments.
These were commonly sold along with the now vintage and antique straight stitch sewing machines. Gradually as the functions that these tools accomplished were integrated into the body of the newer sewing machines their use fell out of favor. Clothing styles changed, became simpler with less decoration, and this too, led to their neglect. However, for my own use, I like the idea that these are separate from the machine, for this reason: The less "gadgetry" in the body of a sewing machine the less can go wrong with it if something breaks. Modern machines have so many functions, but if one small thing breaks they are pretty much useless, or the cost of repair is astronomical. If one of these little attachments breaks, and they rarely do, your sewing machine is still functional, you can still keep sewing, and your project is not being affected by the broken attachment. Then you can look for another attachment to replace the broken one.
Singer and Greist were the 2 main companies that made these attachments but there were others. Singer made different boxes to keep the attachments together and stored safely; one of the first boxes was a "puzzle box", made of pretty wood, it rolled out flat to reveal the attachments all laid out in order ready for use. Later the Singer boxes were green cardboard. Greist attachments often are found in purple velvet lined tin boxes. I've used both brands, and have a slight preference for the Greist.
It takes some practice to get good with using these attachments. I find them fun and challenging to use. It's a "where have you been all my life" sort of feeling. I cut up wide strips of muslin and practice making the hems, or ruffling a strip, sew on bias tape, or sew on a pretty braid using the underbraider. I have a sample piece that shows the different buttonholes that the buttonholer can make. I keep these in a basket as reference for what I want to do on other projects.
The buttonhole attachments makes better button holes than my modern machine does, or that I can do by hand. Finding that was a real gem.
I don't yet have the Hemstitcher, Zigzagger, or Blindstitcher so can't write about the experience of using those. They get kind of pricey on e-bay, so I'm waiting and watching, and searching for ones that I can afford.
Happy sewing. Edey