one's own work, something one made oneself
奴の自作の詩だ
It's a poem he wrote himself.
— いまを生きる (1989)
自作なんだ
I made it myself.
— デッド・ドント・ダイ (2019)
彼らはパソコンを趣味で自作している。
They build their own computers as a hobby.
彼はその少女のために自作の曲を一曲弾いた。
He played one of his own songs for the girl.