I found this information about attachments when researching my new featherweights.
Original Featherweight Attachments
1937 - Foot Hemmer, Adjustable Hemmer, Binder,Tucker, Ruffler, and Cloth Guide
1941 and 1946 - Foot Hemmer, Adjustable Hemmer, Binder, EdgeStitcher, Gatherer, and Ruffler.
1952 and 1955 - Foot Hemmer, Adjustable Hemmer, Multi-SlottedBinder, Edge Stitcher, Gatherer, and Ruffler.
1964 - Zipper Foot, Binder, and SeamGuide. Optional extras are listed as Buttonholer, Edge Stitcher, Gatherer, Foot Hemmer, Quilter, Ruffler, and Tucker. This book is for the Standard white model 221K7 although it's dated 1964 and other references to the 221K7 that I've seen say it wasn't introduced until 1968.
1977 - Foot Hemmer, Seam Guide, Binder,Zipper Foot, and Ruffler. Optional extras are Automatic Zig-Zagger,Buttonholer, Edge Stitcher, Gatherer, and Tucker. This book says Rev 1177 and may be a reprint. The machine appears to be white but is gear driven, has the longer bed extension, a toggle light switch and a different bobbin winder than the others. The face plate is painted like the standard 221K. The case is like the standard 221K except that it has 2 closure latches. I think it is for a model 221K5.
All of the above attachments are the same as the ones that came with other straight-stitch low shank Singer models of the same year except for the foot hemmer which was different for Class 15 and Class 66 machines. The FW uses the Class 15 foot.
The only attachment made specifically for the Featherweight that I've seen is the darning and embroidery attachment. It consists of a very large feed dog cover and a darning foot. The box says it fits 15 Class and 221 machines. The date is 1952. The feed dog covers were either black or chrome.
Hope this information is what you need to complete your set!!! Enjoy your FW; I sure love mine!!!