All kinds of feet are available. There is a plastic quarter inch foot and a metal one with a guide built in (just like my Bernina foot for the same purpose.) Also, all the standard sewing feet, like a zipper foot.
There are many sources and a commercial wholesaler, Brewster, sells all kinds of pieces and parts for the Featherweight. This was not so about 20 years ago, but now the popularity has increased supply.
They all work with a screw that inserts in the side and screws into the bar coming down. Easy peasy.