Welcome back! Here's the full overview of the grammar for nouns in Norwegian:
1. Masculine en kopp - koppen - kopper - koppene
2. Feminine: ei jakke - jakka - jakker - jakkene
3. Neutral: et teppe - teppet - tepper - teppene
4. One-syllable Neutrals: et skap - skapet - skap - skapene et bord - bordet - bord - bordene
And that's the full standard system for endings and articles - for the Nouns!
WELL DONE!!