Was the ark built by fallen angels?

Answer 1

No it wasn't. According to The Bible story Noah built it with his own hands. It should be mentioned however that the factual truth of the story is seriously doubted, even by leading theologians. Stories much like Noah's had already existed and had been written down for thousands of years before in other countries and cultures, most famously in the so-called Epic of Gilgamesh.

In all probability Noah's tale is simply a Judaic retelling of that Epic.

Answer 2

No, according to religious and biblical accounts, the ark was built by the biblical figure Noah and his family under the guidance of God. There is no mention of fallen angels being involved in its construction.