You can only gift the furniture from the current hunt. Make sure the item isn't equipped in your room, and you'll be able to send it like any other gift. Should appear first or last in the gifting page. ??
Yeah i learned the hard way with my Kandi Green Box. Once you use the furniture, you cant remove it unless you replace it with another piece of furniture. If you plan on gifting furniture, just make sure you dont use it on your room. Otherwise, to know if furniture is giftable, it should be the first item(s) is your locker when you gift somebody. If it's from this hunt and it's not there, you need to restart the app and it should show up.