Placing them vertically takes up too much space, so lay them horizontally and try to pack them as tightly as possible.
Since standing them up takes up too much space, lay them flat and arrange them as tightly as possible.
こんにちは！
ご質問ありがとうございます。
ご質問について、いくつか言い方が考えられますが、例えば、
Placing them vertically takes up too much space, so lay them horizontally and try to pack them as tightly as possible.
とすると、『縦向きに置くと面積を取るから[横向き](https://eikaiwa.dmm.com/uknow/questions/117513/)にしておいてなるべく敷き詰めて』
Since standing them up takes up too much space, lay them flat and arrange them as tightly as possible.
とすると、『立てて置くと面積を取るから寝かせて置いてなるべく敷き詰めて』となります。
参考になれば幸いです。
日本 
