The foam float in my Isspro fuel cell sender (the vertical aluminum tube kind, not the swinging arm) is disintegrating and swelling.
It needs to slide freely inside the tube, and also holds a small magnet that actuates the reed switches on a circuit board.

Rather than buy a $100 replacement sender, I was hoping to fix the float. There does not seem to be a service part available.

Any thoughts as to materials I could use to fabricate a new one? It's a half-cylinder about 1" long, 3/4" high with the magnet embedded in the flat side.
It could be electrically conductive (brass shim stock?) because the resistors and switches are on the other side of the PC board.
Would cork stand up to modern E10 gas?
Or maybe coat the existing foam piece with something fuel-resistant but that also won't dissolve the foam...

These guys were helpful when I updated my fuel system.

https://www.harmonracingcells.com/

Got a pic, can’t visualize it
Does it have to be foam?

Sorry, no pics, I clearanced it slightly and put it back in. It's working for now.

No, the float doesn't have to be foam, anything that floats in gasoline and won't disintegrate or absorb it. Fastening the magnet might be a problem if making a brass float though. There are few adhesives that withstand continuous immersion in gas...

Shouldn’t be any problem, JB Weld Steel Stik is gas resistant.
Get a normal float and glue the magnet on it.

When fully cured, J-B Weld is completely resistant to water, gasoline, and about every other petroleum product or automotive chemical. For wet-surface or submerged water or gasoline repairs, try our SteelStik or WaterWeld