It’s fairly expensive, though.

Tin foil of course was replaced by aluminum foil after WWII but a lot of people refer to aluminum foil as tin foil today, as a nod to the original composition.

Tin is approximately twice the density of aluminum so your hat will be heavier if you use tin. But it will provide more protection from electromagnetic radiation of all types. Not sure if tin will have the same behavior as aluminum with regards to emitting xrays when hit by beta particles. Should be researched before you start your chapeau project.