If there is something you want but they don't sell it at stores, you can just make it yourself.
If you can't find what you are looking for at a store, perhaps you could make it by yourself.
ーIf there is something you want but they don't sell it at stores, you can just make it yourself.
「欲しいものが店に売っていなかったら、自分で作ればいい」
you can just make it yourself で「自分でそれを作ればいい」
ーIf you can't find what you are looking for at a store, perhaps you could make it by yourself.
「探しているものが店になかったら、自分で作れるだろう」
can't find what you are looking for at a store で「探しているものが店で見つからない」
to make it by yourself で「自分でそれを作る」
ご参考まで！
ご質問ありがとうございます。
・If they don't sell it at stores, just make it.
＝「お店で売っていなければ（自分で）作ればいいよ。」
（例文）I want this but I don't think they sell it in stores in Japan.// If they don't sell it at stores, just make it.
（訳）これ欲しいけど日本のお店で売っていないと思う。//お店で売っていなければ（自分で）作ればいいよ。
お役に立てれば嬉しいです。
Coco
カナダ 
日本 
