Take another look at the sentence:
On Christmas Eve, Captain Beane wore a pair of antlers while greeting passengers boarding his 727. The costume __________ little trust in Louise, whose fear of flying required a serious pilot.
The sentence requires the past tense of build, an irregular verb. Built is the simple past form.
|Verb||Simple Present||Simple Past||Past Participle|
Builded, the form you chose, is a spelling error. Before you continue, review the rules for irregular verbs.