Performing one's own work: when the creator of a play, piece of music, etc., performs it themself.
その舞台は脚本家が主演した自作自演だった。
That stage production was a self-written, self-performed piece with the playwright starring.
彼は自作自演でピアノ曲を録音した。
He recorded a piano piece that he wrote and performed himself.
Doing everything oneself: handling everything from preparation to execution by oneself.
インディーズバンドは自作自演でアルバムを作り、販売も自分たちで行った。
The indie band made their album entirely by themselves and also handled sales on their own.
小さな会社は広告も販促も自作自演で行っている。
The small company handles advertising and promotions all by itself.
A put-up job or charade: staging an event or incident to appear genuine while it is actually contrived by the same people.
あの炎上は自作自演ではないかとネットで疑われている。
People on the internet suspect that that controversy was a put-up job.
内部告発で自作自演の手口が明らかになった。
A whistleblower revealed the methods used for staging the put-up job.
Sock-puppeting: pretending to be multiple people online (e.g., posting fake support for oneself), a colloquial internet-era meaning.
あのアカウントは自作自演で評価を上げていたと報じられた。
It was reported that the account was boosting its ratings through sock-puppeting.
商品のレビューが自作自演ではないかと消費者から指摘があった。
Consumers pointed out that the product reviews might be self-generated (sock-puppeted).