Question:
Can a rusting washing cup be used for hamotzhi or neggel vasser or mayim acharonim lchatchilla? It doesn't have a hole, just a little rust inside and out.
Answer:
The rust is not an issue and you can use the cup for all three uses. Rust is only an issue when you want to tovel the actual cup, or when the cup has to be koshered, but not in regard to regular washing your hands.
Best wishes