Have you ever seen a zig zag foot before? One of the ladies at the T.O.G.A. had one.
The Necchi, first imported from Italy in 1947, introduced the zig-zag machine to domestic sewing. Invented in the late 19th century, zig-zag machines had previously been used only for industrial sewing. When creating a zigzag stitch, the back-and-forth motion of the sewing machine's needle is controlled by a cam. As the cam rotates, a fingerlike follower, connected to the needle bar, rides along the cam and tracks its indentations. As the follower moves in and out, the needle bar is moved from side to side. Sewing machines made before the mid 1960s mostly lack this hardware and so cannot natively produce a zigzag stitch, but there are often shank-driven attachments available which enable them to do so.
Here are a couple of pictures of the box and instruction manual.