。
She plans to make one more blouse to go with her outfit.
Literal
She [topic-は] outfit [to-に] match-like blouse [object-を] one-more [counter-着] make intend is.
衣装 is 'outfit, ensemble, costume' — fancier than 服, often used for traditional dress, stage costumes, or coordinated looks. 合うような adds the simile/approximation suffix ような ('something like one that matches'); the ~ような softens what would otherwise be a strict 'matches' into 'something fitting/coordinated.' もう一着 uses the counter 着 (ちゃく), specifically for items of clothing — primarily kimono and other 'wearable units.' つもりだ closes with explicit intention.