you can adapt a hassie compendium to the 240 easily. the old ones are cheap, and good.
A "Lindahl Standard Bell-O-Shade" is a little clunky, but quite servicable.
d
"One of the painful things about our time is that those who feel certainty are stupid,
and those with any imagination and understanding are filled with doubt and indecision"
I have long used the Hasselblad compendium shade/filter holder for a large format camera sun shade. I also use the Hassey Chimney finder for ground glass viewing and fine focusing. It just seemed like the right thing to do!
Chimney finders make great loupes. I've used my Bronica S2a finder the same way. It's got Nikon optics, focuses, and has a square base that gets into the corners.
And I've used my hand. I have several photos with unfortunate proof of that. Lens hoods can be improvised out of scrap mat board. An inverted U-shaped cutout on the back of the hood permits the back of the hood to be slipped behind the back of some shutters. A cutout on the bottom provides access to the shutter. Of course the interior should be painted black. With a little ingenuity the design can be modified to be collapsable.
I also sometimes lower my focusing cloth (black side down) over the belows, lens, and all, like a long tunnel. Adjust the position so it forms a "hood" over the whole front end of the camera, and takes care of any light leaks in the bellows to boot. If the fabric is heavy enough, it won't hang down in front. I read about an old-timer doing this, but can't remember who.
I use some black foam code that is taped together to form a 90 degree angle. I hold it over the lens and visually check to make sure the sun isn't falling on the lens. Not as eloquent as a compedium, but works most of the time.
Perhaps it is too late to consider, but I would recommend stepping up to 77mm filters. There are many good quality collapsible rubber lens shades available on EBAY. One nice advantage of these hoods is that the filter can be screwed on into the front of the hood, if you buy one with a front thread, without having to take the hood on and off.