You either use "maison" or "fait maison". Une confiture maison. Des confitures maison. → "Maison" doesn't take "s" here. Une confiture faite maison. Des confitures faites maison. → "Maison" doesn't take "s" here. The reason you don't add "s" is logical. Even if you prepared plenty of jam, you still made it at one home. That said, even French speakers struggle with these subtleties and will readily forgive you if you add an "s".

For food, it's best to say "maison" but for crafted things, it's better to say "fait à la main". Ex : une poupée fait à la main.