I see them all the time in my thrift shop adventures. Odd looking contraptions used to make buttonholes on your home creations. I gathered a few and never used them until maybe a year ago. How foolish. These things are fun, and do an amazingly nice job. Be warned, they are crazy to watch and they make a lot of noise. An "entertains kids and pets" kind of thing. For those interested in learning to sew, here's a good example of economy. Save yourself some money and get a good older machine then add some fun stuff to make it more useful, like a buttonholer. You won't have a one step computerized buttonhole, but this is pretty good and costs a lot less.
Usually the buttonholer box has a small manual in it. To help make it easier to understand and a bit less scary, here are some visuals on set up and use. The manual will tell you about changing the settings, making samples and where to start on the garment. Enjoy!
Low Shank. Not all will fit all machines. Check This before you buy one. This is shown on a Singer 15-91.
Fit hook over needle screw as you put it on.
Set template in, moving the plate if necessary
Screw cloth plate onto bed. This can be hard to do.
I use tape to secure the front.
Now, here is a buttonholer in action....