You can make one
I buy sheets of Viton from McMaster carr to make fuel pump and carb diaphragms
Kalrez will also work for all modern fuel blends but it’s very very expensive
Pure nitrile should also work according to most chemical compatibility references.
McMaster also has fiber re-enforced versions of these materials in different thicknesses explicitly made for our applications
-s
The problem is that those diaphragm are not flat. They are also tiny, and affixed to a tiny shaft by who knows how.
