Here are a couple of other links for Featherweight attachments.
http://www.quiltingboard.com/vintage...s-t169775.html
https://singer-featherweight.com/blo...ts-accessories
Basically any low shank foot for straight stitch machines will work with a Featherweight. Most of the feet and attachments that meet that description will also work on many low shank zig-zag machines (of course you can't zig zag stitch). I used to use the Singer buttonholer and other Singer feet on my zigzag Alco machine (bought new in 1972).
Many (but not all) of the Singer feet and attachments have numbers on them, but some other makers do also.
Perhaps, if you have something that isn't listed in one of the above links, you can post the number and/or picture with something for scale. Maybe someone would know what it is and machine/s it goes with.
Janey - Neat people never make the exciting discoveries I do.