My father used to very frequently make thermostat gaskets from gasket material sheet, and also used non-corrugated cardboard (like cereal box) for some places. He also would rebuild the starter and alternator, replacing brushes burnishing the commutator or slip rings, etc. Rochester carbs too, from the old Pontiac Catalina wagon. I know how to do these things because I learned from him.
Today's youngsters are mostly very spoiled today on all these ready made parts. OK some jobs are too big for certain people and sometimes the factory made part is more advisable, but here really should be a class taught in grade 11-12 on "self reliance and craftsmanship". I realize that is probably not included in the gummint objectives. The school I attended only offered home economics, which I took because it was full of chix.. So get that cereal box out, and trace the old gasket or the base of the comp.. and "just do it".