I’m really curious how you managed to get it to 3 hours. The edit I did ended up at 2:30. And I used just about everything I could find. The only thing I held off on was the serious amount of exterior ship footage. But even then it isn’t that much.
Well I almost did it was aroun the 2:55:00 I used everything that look right from all the documentaries.
Sources were
Giger’s Alien 1979
The Alien Legacy 1999
The Alien Saga 2002
The Beast Within 2003