"We want teaspoons!"
Translation:אנחנו רוצים כפיות!
yes the plural form of כף is כפות. the rule is that every singular noun that have "ית" suffix get ו between the י and ת in the plural form.
I משאית (truck, lorry) -> משאיות; I חצאית (skirt) -> חצאיות; I רגלית (I'm not sure how to translate it, it comes from the word רגל - leg, and it's purpose is to stabilize objects, like when you "park" the bicycle and pulling the little handle that connected to the cogset to prevent the bike from falling over the side) -> רגליות