作つくり損そこなう

godan verb (-u)

fail to make; mess up making; botch the making of

Used when someone attempts to create or build something but fails or makes a mistake in the process.

• ケーキを作つくり損そこなって、ぐちゃぐちゃになった。

  I messed up making the cake and it became a mess.

• 模も型けい飛ひ行こう機きを作つくり損そこなったので、飛とばなかった。

  I botched the model airplane, so it didn't fly.