I downloaded the MP3 of Let It Go, and in Audacity, I took small clips of the words and merged them together in my own audio file. Some issues I ran into were varying lengths of words--notice how "stand" is much longer than words such as "girl", although both are one syllable, which makes it sound slightly unnatural, but I suppose it retains the lyric aspect of Let It Go. 

Also, volume was an issue...Let It Go starts off quietly, but then the volume increases significantly after the bridge and during the chorus, so words taken from those segments were much louder. To fix this I changed the amplification of those segments in order to unify the sentences better.