This is the 13868th most frequent Korean word.
만들었을
"Made" or "created" (past tense modifier).
The word '만들었을' is used as a verb in past tense, combined with '때', to denote an action that occurred at the time being referred to.
나는 어제 작은 나무 상자를 만들었을 때 참 재미있었어요.
I had a lot of fun yesterday when I made a small wooden box.
Here, '만들었을' is combined with '결과' (result) to specify the outcome of a past action of creating something.
우리는 팀 프로젝트에서 웹사이트를 만들었을 결과가 아주 만족스러웠어요.
The result of making the website during the team project was very satisfying.
Here, '만들었을' serves to specify the time context of the making action, highlighted by '때의 노력' (effort during the making).