It's less about magical feelings but rules that native speakers know but aren't aware of. Toaster is clearly male because nouns constructed from verb+er are always male.

Also "male gender" is kinda misleading, it's basically a mistake early linguistics made because it was so centered around Indo-European languages. The modern term is noun class, and Indo-European languages share the trait that they have three noun classes, one containing the word for "woman", the other the one for "man", and another the word for "thing". That's where the names come from: Bridges aren't female in German they simply share a noun class with women.

And girl is neuter in German because all diminutives are. "Deern" is definitely female.