This is a site of a professional photographer that likes to tinker a bit.
One of his projects puts an Arsat Kodiak 30mm lens used on a Salut-S on a 4x5 Speed Graphic making it a large format fisheye. I've wanted one of those lenses for my Salut-S but, where they used to be plentiful and could be had for $165, they are hard to find and are up around $250. Bummer. It could have be fun. But the project of his I'm interested in (Blaine, are you paying attention?) is where he assembles diopter lenses in a tin can, mounts them on a shutter, and has a soft focus portrait lens. The thing with old soft focus portrait lenses is that they are not just soft focus but they do glowy things to specular highlights. Soft focus portrait lenses are hard to find for under $300. I'm sure diopters can be had for less. I'm sure Blaine has lots of these diopters laying around.
Hand-Assembling Lenses for the View Camera
And do check out his magazine articles.