This is cute but it would be better if it had a bigger opening at the top.
This is a nice water bottle but it needs a bigger mouth to put ice in.
ーThis is cute but it would be better if it had a bigger opening at the top.
「これ可愛いけど、もっと口が大きかったら良かったのに。」
水筒の口の部分は opening at the top のように言えます。
ーThis is a nice water bottle but it needs a bigger mouth to put ice in.
「これ素敵な水筒なんだけど、氷を入れるのにもっと大きな口がないとね〜」
「水筒」water bottle
水筒の口を mouth と表現してもオッケーです。
put ice in で「中に氷を入れる」
ご参考まで！
This is so cute! I just wish the opening were wider.
This is so cute! I just wish the opening were wider.
It’s really cute, but I wish it had a wider mouth.
This is adorable! Too bad the opening is a bit small.
I love this! I just wish it came in white.
「可愛い！でも、もっと○○だったらいいのに」は英語では、
"I wish ..."
「〜だったらいいのに」
を使うととても自然です。
カナダ 
アメリカ合衆国 
