For your consideration, here is a Singer Buttonholer Attachment, no. 160506, with instruction booklet, 5 templates, feed cover plate, thumb screw and case. All of the items have some light wear on them.

The instruction booklet has some wear and is scrunched up a bit. There are 30 pages to the booklet. I have not tested the buttonholer, but it looks to be in good shape. Item pictured is the actual item up for sale and comes from a non-smoking household. (212.237d-2.1hc)